February 2023

Jade: Gemstone Properties & Types

<p style="text-align: left;"></p><span style="font-family: georgia;">Jade: A beautiful and durable material of nephrite or jadeite</span><br /><br />Jade is a commercial term encompassing green, white, black or yellow-brown material that consists either either or both of <b>two</b> different minerals, <b>Jadeite and Nephrite.</b> Jadeite is a sodium-rich aluminous pyroxene; nephrite is a fine-grained, calcium-rich, magnesium, iron, aluminous amphibole. All jade is composed of fine-grained, highly intergrown, interlocking ("matted" or "felted" texture, like asbestos or felt) crystals of one or both of these minerals. <br /><br />Jade is one of the toughest gem minerals known because of the intergrown nature of the individual crystals. The more precious kind of jade, this is a microcrystalline interlocking growth of crystals (not a fibrous matrix as nephrite is.) It only occurs in <a href="https://www.geologyin.com/2014/05/the-formation-of-foliated-metamorphic.html" target="_blank"><b>metamorphic</b></a> rocks.<br /><br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgloSbypVvHTXlM-wysWZym6Up712hCmwLY1dawN1fn0KnMMX_ImoXmx6URN226NCF3cNQbJESfkmN0U3WLMdohirqL9UdyLxCNt25gsXxuNx3EJ2sygdwTllzjtM1ibpgD6qZz0C9yvS2ao-JACn4jXg9SDS_D5ikPNvby__L1vz8jsM0CW6lCjWl5/s1080/The%2018-ton%20Polar%20Pride%20boulder%20.jpg" style="margin-left: auto; margin-right: auto;"><img alt="Jade: Gemstone Properties & Types" border="0" data-original-height="1080" data-original-width="1080" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgloSbypVvHTXlM-wysWZym6Up712hCmwLY1dawN1fn0KnMMX_ImoXmx6URN226NCF3cNQbJESfkmN0U3WLMdohirqL9UdyLxCNt25gsXxuNx3EJ2sygdwTllzjtM1ibpgD6qZz0C9yvS2ao-JACn4jXg9SDS_D5ikPNvby__L1vz8jsM0CW6lCjWl5/w400-h400/The%2018-ton%20Polar%20Pride%20boulder%20.jpg" title="Jade: Gemstone Properties & Types" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Jade:
 Gemstone Properties & Types. The 18-ton Polar Pride boulder was 
discovered at the Polar mine in 2000, Canada. Photo: Jade West Group<br /><br /></td></tr></tbody></table>The <b>two jade minerals</b>, nephrite and jadeite are both tough and have small granular crystals giving a fibrous appearance. They have quite different chemical compositions and structures. Nephrite is a type of amphibole mineral and jadeite is a type of pyroxene mineral. Nephrite can be white, yellow, green and brown to black, depending on the amount of iron and magnesium in the mineral. Jadeite can be green, pink, purple, brown and white.<br /><br /><div style="margin: 0px auto; width: 100%;">
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</div><br />Nephrite jade is very <b>tough</b>, the toughest known natural mineral, three times tougher than ceramics and even tougher than steel. This explains why it was used in neolithic times for knife blades, axe heads and later for ornamental carvings. While it is not as hard as some other minerals like diamond, nephrite is made from an interwoven meshwork of fine fibres or needle-like crystals so is not brittle and does not break easily. Coarser crystals and alignment of minerals decreases the toughness of the mineral. Jadeite is the second toughest mineral known, but is not as tough as nephrite as its interlocking crystals are less fibrous.<p></p><p style="text-align: left;"><b>Nephrite</b> is by far the more common form of jade. Nephrite ranges in color from mid to dark green or grey-green, but it can also be white, yellowish or reddish. Nephrite is slightly softer than jadeite. <br /><br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><img alt="imperial jade gemstone, Jade: Gemstone Properties & Types" border="0" data-original-height="1000" data-original-width="1000" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNEuKrJ8oxQORA5_w8UoOcG6DKGm-suNNX9XCqe9_IFpejvkq7M5Zc2TssS8UBxphG12RrShDAE6uK73StIu6gLcYTWNShcxCHl87E_-KxhYg3ODPrV88jSmgdFHXR_iHTAb7_kf0WmpvPMPB4cYz1WgIwNHypEaPMkxLfMdpzYneYZcelrrbSiNFy/w320-h320/imperial%20jade%20gemstone%20(1).jpeg" style="margin-left: auto; margin-right: auto;" title="Jade: Gemstone Properties & Types" width="320" /></td></tr><tr><td class="tr-caption" style="text-align: center;">imperial jade gemstone</td></tr></tbody></table><p></p><div class="separator" style="clear: both; text-align: center;"></div><br />The rarest and most <b>valuable</b> jadeite is called <b>imperial jade</b>, colored by traces of chromium. It has color and transparency rivaling fine emerald, though imperial jade is slightly more yellow in tone than emerald. <br /><p></p><h3 style="text-align: left;"><span style="color: #2b00fe; font-family: georgia;">Physical Properties</span></h3><p style="text-align: left;"><b>Crystal System:</b> Monoclinic<br /><b>Habit: </b>Commonly massive. Fibrous crystals, densely matted together. Usually found as water-washed pebbles or boulders. Rare botryoidal habit known.<br /><b>Hardness: Nephrite</b>: 6 - 6.5    <b>Jadeite</b>: 6.5 - 7<br /><b>Toughness:</b> Extremely tough<br /><b>Cleavage:</b>2 directions; not evident in jade<br /><b>Fracture: </b>Splintery<br /><b>Specific Gravity: Nephrite</b>: 2.90 - 3.02    <b>Jadeite</b>: 3.3 - 3.5 <br /><b><span style="color: #2b00fe;">Chemical formula: </span></b><b><br />Nephrite: </b><span style="font-size: medium;"><span style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; display: inline; float: none; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">Ca</span><sub style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 1; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">2</sub><span style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; display: inline; float: none; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">(Mg,Fe)</span><sub style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 1; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">5</sub><span style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; display: inline; float: none; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">Si</span><sub style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 1; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">8</sub><span style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; display: inline; float: none; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">O</span><sub style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 1; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">22</sub><span style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; display: inline; float: none; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">(OH)</span><sub style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 1; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">2<br /></sub></span><b>Jadeite: </b><span style="font-size: medium;"><span style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; display: inline; float: none; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">Na(Al,Fe</span><sup style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 1; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">3+</sup><span style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; display: inline; float: none; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">)Si</span><sub style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 1; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">2</sub><span style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; display: inline; float: none; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">O</span><sub style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; font-family: georgia; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 1; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">6</sub></span></p><p style="text-align: left;"><span style="font-size: small;"><sub style="-webkit-text-stroke-width: 0px; background-color: #f8f9fa; color: black; font-family: times; font-style: normal; font-variant-caps: normal; font-variant-ligatures: normal; font-weight: 400; letter-spacing: normal; line-height: 1; text-align: left; text-decoration-color: initial; text-decoration-style: initial; text-decoration-thickness: initial; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px;"></sub></span></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzPItcvw2SIj15T7qLaUeusdVHRcb0ruIVLee58roDsJV16l9XJ-NR6r1L7oft-ln4CiAIjaImJAhRT6lJnR-127nQ_jGeCMqfvp-rXtOiwlwKoPN5Vesha0zCtHBnm4kKDsKDAe93ma3OgO8ID6IjEV-L5WE51mwUbArbeMD9Oa55YsKCgBCeABDZ/s1289/Nephrite%20and%20jadeite.jpg" style="margin-left: auto; margin-right: auto;"><img alt="Nephrite and jadeite" border="0" data-original-height="840" data-original-width="1289" height="418" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzPItcvw2SIj15T7qLaUeusdVHRcb0ruIVLee58roDsJV16l9XJ-NR6r1L7oft-ln4CiAIjaImJAhRT6lJnR-127nQ_jGeCMqfvp-rXtOiwlwKoPN5Vesha0zCtHBnm4kKDsKDAe93ma3OgO8ID6IjEV-L5WE51mwUbArbeMD9Oa55YsKCgBCeABDZ/w640-h418/Nephrite%20and%20jadeite.jpg" title="Nephrite and jadeite" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small;">Jadeite (left) and </span>Nephrite (right).<br /></td></tr></tbody></table><span style="font-size: small;"><br /></span><p></p><p style="text-align: left;"></p><h4 style="text-align: left;"><span style="font-family: georgia;">Formation</span></h4><p style="text-align: left;"><b>Jadeite</b> and nephrite are only found in metamorphic rocks, formed in current or ancient subduction zones. Jadeite is found in rocks that formed under higher pressure than nephrite. Most known deposits of jadeite occur along, or near faults in serpentinites. Examples of this type of deposit are found in Myanmar, New Zealand, Canada, Taiwan, Guyana, Surinam, southern Europe, Russia and China. In Australia, nephrite is mostly found as long lenses, within marble of Early to Middle Proterozoic age (2500 - 1000 million years ago). </p><div style="margin: 0px auto; width: 100%;">
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</div> <br /><p></p><p style="text-align: left;"><b>Nephrite</b> is common products of low-level regional metamorphism (green shale facies), and contact metamorphism of basic and ultrabasic rocks and dolomites. Nephrite consists of a microcrystalline interlocking fibrous matrix of the calcium, magnesium-iron rich amphibole mineral series tremolite (calcium-magnesium)-ferroactinolite (calcium-magnesium-iron). The middle member of this series with an intermediate composition is called actinolite (the silky fibrous mineral form is one form of asbestos). The higher the iron content, the greener the colour. <b>Tremolite</b> occurs in metamorphosed dolomitic limestones and Actinolite in metamorphic greenschists/glaucophane <a href="https://www.geologyin.com/2014/05/the-formation-of-foliated-metamorphic.html" target="_blank">schists</a>.<br /></p><p style="text-align: left;"></p><h4 style="text-align: left;"><span style="color: #2b00fe; font-family: georgia;">Nephrite jade : trade names</span></h4><p style="text-align: left;"><b>Black nephrite jade:</b> a generic term referring to all black or almost black nephrite jade, which is usually caused by microscopic inclusions of dark minerals, mainly graphite.<br /><br /><b>Hetian Jade:</b> one of the classic Chinese jades. It consists almost entirely of tremolite, but can contain up to 5% by weight of impurities such as diopside, epidote, clinozoisite, olivine, dolomite, quartz, magnetite, pyrite, apatite, limonite and carbonaceous matter.<br /><br /><b>Kunlun Jade: </b>one of the classic Chinese jades, also known as "Qinghai Jade". It consists of actinolite and tremolite in varying proportions, and generally also contains minor wollastonite. The most precious specimens have green-white patterns.<br /><br /><b>Lantian Jade:</b> a variety of tremolite (white jade), which varies in color from white to yellow, gray, pale blue and light green. The colors are due to the inclusions of iron oxides (yellow), graphite (gray) and chlorite, epidote or minerals of the serpentine group (pale blue).<br /><br /><b>Manasi Jade:</b> a green jade which consists mainly of tremolite with only minor actinolite. The green color is caused by microscopic inclusions of green silicates, mainly chlorite and minerals from the serpentine group, and it also frequently contains diopsides and grossulars.<br /><br /><b>Meiling Jade:</b> a typical tremolite jade, in a variety of colors from white to gray. The white varieties are the most precious.<br /><br /><b>Tremolite Jade: </b>a generic term, referring to all varieties of nephrite which consist mainly of tremolite. While all white jades are tremolite jades, not all tremolite jades are white.<br /><br /><b>Xiuyan Jade:</b> a green jade, which contains both tremolite and actinolite in varying proportions. Some varieties may also contain antigorite (Zhang, 2002). One of the classic Chinese jades.<br /></p><h4 style="text-align: left;"><span style="color: #2b00fe;">Jade jadeite : trade names</span></h4><p style="text-align: left;"><b>Fei cui jade: </b>is the most popular variety of jade jadeite. Rarely also blue, lavender-purple, black, red or yellow, depending on the impurities.</p><p style="text-align: left;"></p><h4 style="text-align: left;"><span style="color: #2b00fe; font-family: georgia;">Fake Jade: Green ornamental stones commonly mistaken for jade<br /></span></h4><p style="text-align: left;"><b>Transvaal Jade:</b> A compact variety similar to green grossular jade containing up to 25% zoisite. Often called "hydrogrossulaire", the water content may be due to the zoisite component rather than a real hydrogrenate.<br /><b>Queensland Jade:</b> is a natural green to yellow chrysoprase grown in Queensland, Australia.<br /><b>California jade:</b> is an idocrase (vesuvianite), extracted in the Butte County, near Chico, in California, it is a translucent yellow-green stone also called "californite", it is proposed as an alternative to jade.<br /><b>African jade: </b>is the other name for buddstone, a variety of fuschite and green serpentine from South Africa.</p><p style="text-align: left;"><span style="font-size: medium;"><b>See also: <a href="https://www.geologyin.com/2016/12/the-giant-nephrite-jade-road-in-canada.html" target="_blank">Giant Nephrite Jade Discovered in Canada</a><br /><a href="https://www.geologyin.com/2016/11/giant-jade-stone-worth-170-million.html" target="_blank">Giant Jade Stone Worth $170 Million Unearthed in Myanmar</a></b></span><br /></p>

Jade: Gemstone Properties & Types

Jade: A beautiful and durable material of nephrite or jadeite Jade is a commercial term encompassing green, white, black or yellow-brown mat...

The Mohs Hardness Scale: Comparing the Hardness of Minerals

Crystal, Geology, Mineralogy 9:15 PM

<p></p>The Mohs Scale is a qualitative hardness scale that ranges from 1 to 10, describing the ability of a harder mineral, such as a gemstone or diamond, to scratch other softer stones or minerals. One thing to keep in mind is that the scale is purely an ordinal scale. That being said, sapphires are <b>twice</b> as hard as <b>topaz</b> and diamonds are <b>four times </b>as hard as sapphires, despite their numbers on the Mohs hardness scale. <p>A mineral's <b>hardness</b> is its ability to resist scratches. A <b>mineral's toughness </b>is its ability to resist being fractured. Below is a list of some of the most common gemstones we work with, including their ranking on the Mohs hardness scale as well as its toughness.<br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwAtnqjCwVWUtIZUAJUSUE8_LdDD0j4ImK8CKFKfRThWkERH7oHhaRq2zmqJ1xjtg0C7XJ9ZVymt0-nOYnvGBBBMROCdBgYU3GCOP66KUJcVmlOfoTFUUJBCMNM3eKcamkxk0NZh1bKeWHEzUMZrtERFZBWo5w9ETvLFITdJJgRIaEJ9LcL-yfBgfV/s2541/Final_Mohs%20Hardness_R.%20Lugo%20(1).jpg" style="margin-left: auto; margin-right: auto;"><img alt="The Mohs Hardness Scale: Comparing the Hardness of Minerals" border="0" data-original-height="1964" data-original-width="2541" height="309" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwAtnqjCwVWUtIZUAJUSUE8_LdDD0j4ImK8CKFKfRThWkERH7oHhaRq2zmqJ1xjtg0C7XJ9ZVymt0-nOYnvGBBBMROCdBgYU3GCOP66KUJcVmlOfoTFUUJBCMNM3eKcamkxk0NZh1bKeWHEzUMZrtERFZBWo5w9ETvLFITdJJgRIaEJ9LcL-yfBgfV/w400-h309/Final_Mohs%20Hardness_R.%20Lugo%20(1).jpg" title="The Mohs Hardness Scale: Comparing the Hardness of Minerals" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The Mohs Hardness Scale: Comparing the Hardness of Minerals<br />The Mohs Scale of Mineral Hardness (created by Friedrich Mohs in 1822)</td></tr></tbody></table><p style="text-align: left;"></p><h3 style="text-align: left;"><span style="font-family: georgia; font-size: medium;"><b><span style="color: #2b00fe;">The Mohs Hardness Scale</span></b></span></h3><p style="text-align: left;">10   Diamond<br />9    Corundum<br />8    <a href="https://www.geologyin.com/2019/10/what-causes-color-in-topaz.html" target="_blank">Topaz</a><br />7    <a href="https://www.geologyin.com/2016/04/major-varieties-of-quartz.html" target="_blank">Quartz</a><br />6    Feldspar<br />5    Apatite<br />4    <a href="https://www.geologyin.com/2017/02/why-fluorite-comes-in-different-colors.html" target="_blank">Fluorite</a><br />3    Calcite<br />2    Gypsum<br />1    Talc<br /></p><h4 dir="ltr" style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;"> Mohs Hardness Testing Tips</span></h4>
<div dir="ltr" style="text-align: left;">
</div>
<ul dir="ltr" style="text-align: left;"><li>A list of minerals in order of hardness can be a handy reference. If
 you determine that a specimen has a hardness of Mohs 4 you can quickly 
get a list of potential minerals.<br /><br /></li><li>Practice and experience will improve your abilities when doing this test. You will become faster and more confident.<br /><br /></li><li>If the hardness of the unknown specimen is about 5 or less, you 
should be able to produce a scratch without much exertion. However, if 
the unknown specimen has a hardness of about 6 or greater, then 
producing a scratch will require some force. For those specimens, hold 
the unknown firmly against the table, place the standard specimen 
against it, press firmly with determination, then holding pressure 
slowly drag the standard specimen across the surface of the unknown.<br /> <br /></li><li>Don't be fooled by a soft standard specimen producing a mark on a 
hard unknown. That mark is like what a piece of chalk produces on a 
blackboard. It will wipe off without leaving a scratch. Wipe your finger
 across the tested surface. If a scratch was produced there will be a 
visible groove. If marks wipe away then a scratch was not produced.</li></ul>

<ul style="text-align: left;"><li>Some hard materials are also very brittle. If one of your specimens 
is breaking or crumbling rather than scratching, you will have to be 
very careful while conducting the test. Testing tiny or granular 
specimens can be difficult.<br /><br /></li><li>Some specimens contain impurities. If the results of your test are 
not visibly conclusive, or if the information from your test does not 
conform with other properties, do not hesitate to do the test again. It 
is possible that a small piece of quartz (or another impurity) was 
embedded in one of your specimens.<br /><br /></li><li>Don't be wimpy! This is a very common problem. Some people casually 
rub one specimen back and forth against another and then look for a 
mark. That is not how the test is done. It is done with a single, 
determined motion with the goal of cutting a scratch.<br /><br /></li><li>Be careful. When you hold the unknown specimen against the table, 
position it so that the known specimen will not be pulled across one of 
your fingers.<br /><br /></li><li>This test should be done on a lab table or work bench with a durable
 surface or a protective covering. Don't do this type of testing on fine
 furniture.<br /><br /></li><li>Test tiny particles or grains by placing them between two pieces of 
an index mineral and scraping them together. If the grains are harder 
than the index mineral scratches will be produced. If the grains are 
softer they will smear.</li></ul><div style="margin: 0px auto; width: 100%;">
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</div><br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2Sh9HNryAM7ctPOMYTBMoG3did-ukx3gQbaGXVLuFXWnRB25zv_l-8GeKrXH1olvzC2zC3_qz51RCXMjVzJfrqqqFjjZzN2iCojAZb8UIiKXxV5efS0pPBBd22s51wDTTW_LNWb-8yYvQUZI2j1NyFsn2d5pELxl7O3g035O1XjmGPPoHR_dhDISX/s3307/Mohs-Hardness-Scale.webp" style="margin-left: auto; margin-right: auto;"><img alt="The Mohs Hardness Scale: Comparing the hardness of minerals" border="0" data-original-height="2339" data-original-width="3307" height="452" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2Sh9HNryAM7ctPOMYTBMoG3did-ukx3gQbaGXVLuFXWnRB25zv_l-8GeKrXH1olvzC2zC3_qz51RCXMjVzJfrqqqFjjZzN2iCojAZb8UIiKXxV5efS0pPBBd22s51wDTTW_LNWb-8yYvQUZI2j1NyFsn2d5pELxl7O3g035O1XjmGPPoHR_dhDISX/w640-h452/Mohs-Hardness-Scale.webp" title="The Mohs Hardness Scale: Comparing the hardness of minerals" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The Mohs Hardness Scale: Comparing the Hardness of Minerals<br />Photo: <a href="https://www.compoundchem.com/" rel="nofollow" target="_blank">CompoundChem</a> Creative Commons <br /></td></tr></tbody></table><p></p>
<div style="text-align: left;">
<h4>
<span style="font-family: "georgia" , "times new roman" , serif;"> Hardness Variations in a Single Mineral  </span></h4>
Most minerals have a fairly consistant hardness. For example, the 
hardness of calcite is always about 3. However, some minerals have a 
range of hardness. <br />
<br />
Minerals that are part of a solid solution series can change in hardness
 as the composition varies. Atomic bonds between some elements are 
stronger than others. An example is garnet which has a composition of X<sub>3</sub>Y<sub>2</sub>(SiO<sub>4</sub>)<sub>3</sub>
 where X can be Ca, Mg or Fe and Y can be Al, Fe or Cr. Garnets with 
different compositions have different hardness. Garnets range in 
hardness from 6.5 to 8.<br />
<br />
Minerals such as kyanite have different hardness in different 
directions. Kyanite is a mineral that frequently occurs in blade-shaped 
crystals. These crystals have a hardness of about 5 if they are tested 
parallel to the long axis of the crystal and a hardness of about 7 if 
they are tested parallel to the short axis of a crystal.<br />
<br />
Weathering can also influence the hardness of a mineral. Weathering 
usually changes a mineral's composition with the weathering product 
usually softer than the original material. When testing the hardness or 
streak or other property of a mineral, the best way to test is on a 
freshly broken surface that has not been exposed to weathering. </div><p> <br /></p>

The Mohs Hardness Scale: Comparing the Hardness of Minerals

The Mohs Scale is a qualitative hardness scale that ranges from 1 to 10, describing the ability of a harder mineral, such as a gemstone or d...

Ikaite And Glendonite

Mineralogy, Minerals 9:29 PM

<p></p><span style="color: white;">Calcite after ikaite var. glendonite</span><p>Ikaite is the mineral name for the hexahydrate of calcium carbonate, CaCO<sub>3</sub>·6H<sub>2</sub>O. Ikaite is colorless when pure. It is usually considered a rare mineral, but this is likely due to difficulty in preserving samples.  Ikaite is a <b>metastable</b> and has only been observed in nature at temperatures <7 °C. </p><p>It was first discovered in nature by the Danish mineralogist Pauly in the Ikka (then spelt Ika) fjord in SW Greenland, close to Ivigtut, the locality of the famous cryolite deposit.<span style="color: white;"><br /></span></p><p>Ikaite Readily dehydrates to calcite above 8°C. The resulting pseudomorph of calcite after ikaite is also called "<b>glendonite</b>."<span style="color: white;"><br />  </span><br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEih2QH42AZ96sKNY0hnWh6xyEonDzeKCkISayUsc0Uoh0qCHhIPoYmCwqA82YL59Ama3ZsA2oHxLnFofqm0Nt6l-WhCpOzGs1Z2OcYFeqVDxyAgrL5yn3eFyvCIsiP9CMEVCdfRI_pa3xhR99zLM8rRZR2o6MUo_f9QE2mn8oALwNvfCb8iIieU9blP/s1124/Ikaite-Calcite-Opal%20%20(1).jpg" style="margin-left: auto; margin-right: auto;"><img alt="Ikaite And Glendonite" border="0" data-original-height="1124" data-original-width="1124" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEih2QH42AZ96sKNY0hnWh6xyEonDzeKCkISayUsc0Uoh0qCHhIPoYmCwqA82YL59Ama3ZsA2oHxLnFofqm0Nt6l-WhCpOzGs1Z2OcYFeqVDxyAgrL5yn3eFyvCIsiP9CMEVCdfRI_pa3xhR99zLM8rRZR2o6MUo_f9QE2mn8oALwNvfCb8iIieU9blP/w400-h400/Ikaite-Calcite-Opal%20%20(1).jpg" title="Ikaite And Glendonite" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"> Ikaite And Glendonite. Precious opal after glendonite <br />from White Cliffs Opal Field, New South Wales, Australia.<br />Photo: Proper_gems/Instagram</td></tr></tbody></table><p><span style="color: white;"></span></p><p></p><p>Natural ikaite growth sites vary widely in their chemical conditions, including saline lakes and fjords (where it forms tufa towers;  cold saline spring waters, Antarctic sea-ice, and marine sediments (up to 10 m below the sediment–water interface). These sites are all characterised by having low temperatures (≤7 °C) and unusual chemical conditions. <br /><br />This "melting mineral" is more commonly known through its pseudomorphs. Ikaite or its pseudomorphs have been reported as occurring in marine, freshwater, and estuarine environments.<br /><br />The aqueous chemical conditions vary, but all are believed to feature high alkalinity in combination with chemical inhibitors of the thermodynamically more stable anhydrous carbonate polymorphs, calcite, aragonite, and/or vaterite.<br /></p><div style="margin: 0px auto; width: 100%;">
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</div><p><br /><br />Furthermore, although in nature, ikaite has only been found in environments with temperatures ranging from −2 to + 7 °C. In nature, ikaite is most commonly found growing below the sediment–water interface in continental shelf settings. </p><div class="wDYxhc" data-attrid="ss:/webfacts:crystal_class" data-hveid="CGYQAA" data-md="1001" data-ved="2ahUKEwjJtdaagbT9AhWUgv0HHQd4AegQkCl6BAhmEAA" lang="en-US" style="clear: none;"><div class="Z1hOCe"><div class="zloOqf PZPZlf" data-ved="2ahUKEwjJtdaagbT9AhWUgv0HHQd4AegQyxMoAHoECGYQAQ"><div class="rVusze"><span class="w8qArf"><b>Crystal class<span class="eTVOZd">:</span> </b></span><span><span class="LrzXr kno-fv wHYlTd z8gr9e">Prismatic (2/m) </span></span></div></div></div></div><div class="wDYxhc" data-attrid="ss:/webfacts:crystal_system" data-hveid="CGMQAA" data-md="1001" data-ved="2ahUKEwjJtdaagbT9AhWUgv0HHQd4AegQkCl6BAhjEAA" lang="en-US" style="clear: none;"><div class="Z1hOCe"><div class="zloOqf PZPZlf" data-ved="2ahUKEwjJtdaagbT9AhWUgv0HHQd4AegQyxMoAHoECGMQAQ"><div class="rVusze"><span class="w8qArf"><b>Crystal system<span class="eTVOZd">:</span></b> </span><span><span class="LrzXr kno-fv wHYlTd z8gr9e">Monoclinic</span></span></div></div></div></div><div class="wDYxhc" data-attrid="ss:/webfacts:formula_repeat_unit" data-hveid="CGsQAA" data-md="1001" data-ved="2ahUKEwjJtdaagbT9AhWUgv0HHQd4AegQkCl6BAhrEAA" lang="en-US" style="clear: none;"><div class="Z1hOCe"><div class="zloOqf PZPZlf" data-ved="2ahUKEwjJtdaagbT9AhWUgv0HHQd4AegQyxMoAHoECGsQAQ"><div class="rVusze"><span class="w8qArf"><b>Chemical Formula</b><span class="eTVOZd">:</span> </span><span><span class="LrzXr kno-fv wHYlTd z8gr9e">CaCO<sub>3</sub>·6H<sub>2</sub>O <br /><b>Color</b>: Chalky white.<br /></span></span></div></div></div></div><p> </p><p></p><h4 style="text-align: left;">Ikaite Pseudomorphs:<br /></h4><p>The presence of ikaite may be recorded through geological time through the presence of pseudomorphs of other calcium carbonate phases after it. Although it can be hard to uniquely define the original mineral for every specimen, there appears to be good evidence for ikaite as the precursor for the majority of the following <b>locality names of pseudomorphs:</b><br /><br />Glendonite, Thinolite, Jarrowite, Fundylite, Gersternkorner, Gennoishi, Molekryds, and Pseudogaylussite. <br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhotKyO7CAUhHNJo2WcxElHpQtdZw8LkE0GZS6jHA9rihPrt3y-UVqAfEsNH_Q-3KbpVHjRc0H-rurvQRSqJZGZxaTjY6SBw8qLt8knFaX0uAAGt1e0_60HI4jKl9h4Wt4nDX7zbWvMFcjRTSpehHqbZn6zCP-MBBfPKKnJuKBlYsGtQdAvfzDbXNbo/s1320/ikaite%20(1).jpg" style="margin-left: auto; margin-right: auto;"><img alt="ikaite (glendonite)" border="0" data-original-height="792" data-original-width="1320" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhotKyO7CAUhHNJo2WcxElHpQtdZw8LkE0GZS6jHA9rihPrt3y-UVqAfEsNH_Q-3KbpVHjRc0H-rurvQRSqJZGZxaTjY6SBw8qLt8knFaX0uAAGt1e0_60HI4jKl9h4Wt4nDX7zbWvMFcjRTSpehHqbZn6zCP-MBBfPKKnJuKBlYsGtQdAvfzDbXNbo/w400-h240/ikaite%20(1).jpg" title="ikaite (glendonite)" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Calcite after ikaite var. glendonite concretion<br />Photo: Brocken Inaglory<br /></td></tr></tbody></table><br /><h3 style="text-align: left;">Glendonite<br /></h3><p>The term “glendonite” does not refer to a mineral, but to a class of <a href="https://www.geologyin.com/2018/04/what-is-pseudomorph-mineral.html" target="_blank">pseudomorphs</a>. A <b>pseudomorph</b> is a mineral that has taken the characteristic crystal shape of another mineral by processes such as replacement or recrystallization. Glendonite named after type locality, Glendon, New South Wales, Australia.<br /><b><br />Glendonites</b> started out life as crystalline masses of <b>ikaite</b>, Ikaite only forms in near-freezing water of high alkalinity, in organic-rich sediments at the sediment-water interface.  At warmer temperatures, ikaite is not stable, and the mineral loses its water content.  It converts to calcite (anhydrous calcium carbonate).  During the ikaite-calcite conversion, the original crystal structure of the ikaite may be retained.  Calcite masses that retain ikaite crystal shapes are called glendonites.  So, glendonite is not a mineral.  Rather, it is a calcite <a href="https://www.geologyin.com/2018/04/what-is-pseudomorph-mineral.html" target="_blank">pseudomorph</a> (“false-form”) after ikaite.<br /></p><p>Marine sedimentary ikaite is the parent mineral to <b>glendonite</b>, 
stellate pseudomorphs found throughout the geological record which are 
most usually composed of calcite. Ikaite is known to be metastable at 
earth surface temperatures and pressures, readily breaking down to more 
stable carbonate polymorphs when exposed to warm (ambient) conditions. 
Yet the process of transformation of ikaite to calcite is not well 
understood, and there is an ongoing debate as to the palaeoclimatic 
significance of glendonites in the geological record.    <br /><br /></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj7sHrRWt00qPrGUijGIUYV6UWzPaA9s-Vvk9QPeF92LjF9vfxjRRwXcnwOTzW_BJEQGPatMnRaiPc5SRGk5yrCbC7My4S2tkZeeHn1cdATkUex8fbA17u9AhdYTC-wNqsbPcSU8l7Ff4qPNIN4qWdnHyVEE_Ev3TArtA0BMXR3jxgsn7RQunCkCh64/s600/%20Ikaite%20And%20Glendonite.jpeg" style="margin-left: auto; margin-right: auto;"><img alt="Ikaite And Glendonite" border="0" data-original-height="507" data-original-width="600" height="338" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj7sHrRWt00qPrGUijGIUYV6UWzPaA9s-Vvk9QPeF92LjF9vfxjRRwXcnwOTzW_BJEQGPatMnRaiPc5SRGk5yrCbC7My4S2tkZeeHn1cdATkUex8fbA17u9AhdYTC-wNqsbPcSU8l7Ff4qPNIN4qWdnHyVEE_Ev3TArtA0BMXR3jxgsn7RQunCkCh64/w400-h338/%20Ikaite%20And%20Glendonite.jpeg" title="Ikaite And Glendonite" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Orange-brown Crystals of Calcite (Var. Glendonite),<br /> from Kola Peninsula, Murmanskaja Oblast', Northern Region, Russia<br />Photo: Rob Lavinsky</td></tr></tbody></table><br /><br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhacxdMQfgNAj7GK4p3CVdj2WaSoohEIuU_mMeT_SpTqz4J-L_at3It84GEIRJPRSOqprPjz-fWQgvPJAbnYbRLL4IlNBHdXd6Gmn2xp3JJ5jT-vgDPldN9RpggzsLZGGNCWjToHnRKHyTHVUVchZkHKLGnoR76pPfsTkf1H5NrdyLYJYiNP2n4AmHv/s1126/Calcite%20after%20Ikaite.jpg" style="margin-left: auto; margin-right: auto;"><img alt="Precious opal after glendonite (White Cliffs Opal Field, New South Wales, Australia)" border="0" data-original-height="657" data-original-width="1126" height="234" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhacxdMQfgNAj7GK4p3CVdj2WaSoohEIuU_mMeT_SpTqz4J-L_at3It84GEIRJPRSOqprPjz-fWQgvPJAbnYbRLL4IlNBHdXd6Gmn2xp3JJ5jT-vgDPldN9RpggzsLZGGNCWjToHnRKHyTHVUVchZkHKLGnoR76pPfsTkf1H5NrdyLYJYiNP2n4AmHv/w400-h234/Calcite%20after%20Ikaite.jpg" title="Precious opal after glendonite (White Cliffs Opal Field, New South Wales, Australia)" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">Precious opal after glendonite <br />(White Cliffs Opal Field, New South Wales, Australia)<br />Photo: James St. John<br /></td></tr></tbody></table><br /><b>See also:</b><br /><a href="https://www.geologyin.com/2016/04/major-varieties-of-quartz.html" target="_blank">The Major Varieties of Quartz (Photos)<br /></a><a href="https://www.geologyin.com/2015/02/top-radioactive-minerals-occurrence.html" target="_blank">Top Radioactive Minerals: Occurrence and Identification</a><br /><br /><p></p>

Ikaite And Glendonite

Calcite after ikaite var. glendonite Ikaite is the mineral name for the hexahydrate of calcium carbonate, CaCO 3 ·6H 2 O. Ikaite is colorles...

Surprise! Earth's Inner Core Has Another Inner Core

Earth News, Geology 9:03 PM

<p></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><img alt="Earth's Inner Core Has Another Inner Core" border="0" data-original-height="952" data-original-width="1200" height="508" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh6nfBboabbnBIs8AbBQcSEffAlpMOdCgT0y4xtyScrRaiG-5VDWSwzzJ2Yv3r44_6yNpHONjCWJEIDjprXGNo0AtcotRWb1WJC4v5LRe3P4NIq1VwhL_d7F-wTxXnXbi2lJ5ZpNpPXQb1WoDKCbHe2bnQYogJ4xpTvnbwXJ8ASUvFInANa6S_WE6IV/w640-h508/Surprise!%20Earth's%20Inner%20Core%20Has%20Another%20Inner%20Core%20%20(1).jpeg" style="margin-left: auto; margin-right: auto;" title="Surprise! Earth's Inner Core Has Another Inner Core" width="640" /></td></tr><tr><td class="tr-caption" style="text-align: center;">Earth's Inner Core Has Another Inner Core. Kateryna Kon/science Photo Library//Getty Images<br /></td></tr></tbody></table><p></p><div class="separator" style="clear: both; text-align: center;"></div><p></p><p>Using seismic waveform data, researchers believe they’ve discovered Earth’s even smaller inner core.  The new inner core is made up of about 400 miles of dense iron, the researchers say.<br /></p><p>By measuring the different speeds at which these waves penetrate and pass through the Earth's inner core, the researchers believe they've documented evidence of a distinct layer inside Earth known as the innermost inner core -- a solid "metallic ball" that sits within the centre of the inner core.<br /><br />Not long ago it was thought Earth's structure was composed of four distinct layers: the crust, the mantle, the outer core and the inner core. The findings, published in Nature Communications, confirm there is a fifth layer.<br /><br />"The existence of an internal metallic ball within the inner core, the innermost inner core, was hypothesized about 20 years ago. We now provide another line of evidence to prove the hypothesis," Dr Thanh-Son Phạm, from the ANU Research School of Earth Sciences, said.<br /><br />Professor Hrvoje Tkalčić, also from ANU, said studying the deep interior of Earth's inner core can tell us more about our planet's past and evolution.<br /><br />"This inner core is like a time capsule of Earth's evolutionary history -- it's a fossilised record that serves as a gateway into the events of our planet's past. Events that happened on Earth hundreds of millions to billions of years ago," he said.<br /></p><div style="margin: 0px auto; width: 100%;">
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</div><br />The researchers analysed seismic waves that travel directly through the Earth's centre and "spit out" at the opposite side of the globe to where the earthquake was triggered, also known as the antipode. The waves then travel back to the source of the quake.<br /><br />The ANU scientists describe this process as similar to a ping pong ball bouncing back and forth.<br /><br />"By developing a technique to boost the signals recorded by densely populated seismograph networks, we observed, for the first time, seismic waves that bounce back-and-forth up to five times along the Earth's diameter. Previous studies have documented only a single antipodal bounce," Dr Phạm said.<br /><br />"The findings are exciting because they provide a new way to probe the Earth's inner core and its centremost region."<br /><br />One of the earthquakes the scientists studied originated in Alaska. The seismic waves triggered by this quake "bounced off" somewhere in the south Atlantic, before travelling back to Alaska.<br /><br />The researchers studied the anisotropy of the iron-nickel alloy that comprises the inside of the Earth's inner core. Anisotropy is used to describe how seismic waves speed up or slow down through the material of the Earth's inner core depending on the direction in which they travel. It could be caused by different arrangement of iron atoms at high temperatures and pressures or preferred alignment of growing crystals.<br /><br />They found the bouncing seismic waves repeatedly probed spots near the Earth's centre from different angles. By analysing the variation of travel times of seismic waves for different earthquakes, the scientists infer the crystallised structure within the inner core's innermost region is likely different to the outer layer.<br /><br />They say it might explain why the waves speed up or slow down depending on their angle of entry as they penetrate the innermost inner core.<br /><br />According to the ANU team, the findings suggest there could have been a major global event at some point during Earth's evolutionary timeline that led to a "significant" change in the crystal structure or texture of the Earth's inner core.<br /><br />"There are still many unanswered questions about the Earth's innermost inner core, which could hold the secrets to piecing together the mystery of our planet's formation," Professor Tkalčić said.<br /><br />The researchers analysed data from about 200 magnitude-6 and above earthquakes from the last decade.<p></p><p> </p><p><u>The above story is based on <a href="https://science.anu.edu.au/news-events/news/bouncing-seismic-waves-reveal-distinct-layer-earths-inner-core" rel="nofollow" target="_blank">Materials</a> provided by <a href="https://www.anu.edu.au/" rel="nofollow" target="_blank">Australian National University</a>. </u> </p>

Surprise! Earth's Inner Core Has Another Inner Core

Earth's Inner Core Has Another Inner Core. Kateryna Kon/science Photo Library//Getty Images Using seismic waveform data, researchers bel...

The Principle of Superposition

sedimentary, Stratigraphy 8:53 PM

<p>The law of superposition, states that the sequence of layers
 observed in sedimentary rocks marks the time of deposition of the 
layers. The lowest layer is the oldest layer of deposition and the ones 
above it are successive younger layers of deposition according to the 
law of superposition definition. Thus, the principle of superposition 
geology is one of the important concepts for explaining the geological 
stratigraphy used widely in the fields of geology, archaeology, and 
other fields related to it. <br /><br />The principle of superposition simply says that when sediments are 
deposited, those which are deposited first will be at the bottom, and so
 the lower sediments will be the older. This is because sediment is 
deposited from above, because gravity operates in a downward direction, 
and because sediment does not readily pass through other sediment.</p><p>The Law of Superposition is a geologic principle, first observed and <b>named</b> by Friedrich von Schiller in 1785.<br /></p><div style="margin: 0px auto; width: 100%;">
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</div><br />When we see the rock formation in paralleled form, the layered sequence of the material such as lava flow or sedimentary layers constitutes a clear shape. In this shape, the bottom layer shows the oldest material and the upper layer shows the youngest material. In the same way, all the layers going from bottom to top are successively younger.<p></p><p></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjPB6wLflIap4UJnlvaHTPYhwY51sreJD1aYBAFiv-zylJb1vtenuTY9zffSgTb6-eXkVpVVYflipy2zYwrrGMZPqujPaGUoaD0UtE5NHgObTNTGZrFxnwNoNcf1e7bdJu2KdY1h76lvjsuKQ9T1tJQSdhdasEzxWnnyATYoIleDo2rVrBwxNDplxSU/s1199/The%20Principle%20of%20Superposition.jpg" style="margin-left: auto; margin-right: auto;"><img alt="The Principle of Superposition" border="0" data-original-height="1057" data-original-width="1199" height="353" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjPB6wLflIap4UJnlvaHTPYhwY51sreJD1aYBAFiv-zylJb1vtenuTY9zffSgTb6-eXkVpVVYflipy2zYwrrGMZPqujPaGUoaD0UtE5NHgObTNTGZrFxnwNoNcf1e7bdJu2KdY1h76lvjsuKQ9T1tJQSdhdasEzxWnnyATYoIleDo2rVrBwxNDplxSU/w400-h353/The%20Principle%20of%20Superposition.jpg" title="The Principle of Superposition" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The Principle of Superposition<br />Sedimentary layers - Argentina <br /></td></tr></tbody></table><br />It is compulsory to examine the rock material before applying the law of superposition. The rocks’ layers are usually formed due to depositional events like lava eruptions. However, this is not necessary for all types of rock structures. The older-to-newer relationship (law of superposition) is different in volcanic and metamorphic rocks.<br /><br />The law of superposition doesn’t work on igneous rocks. The layers in the igneous rocks are formed due to the pressure from the uppermost layer to the lowest layer. Hence, every layer is chaotic. The age of layers isn’t clear in igneous rocks.<br /><br />The law of superposition can be applied to sedimentary rocks because the nature of fossils can accurately specify the age of the rock.<br /><br />The rock layers found in mountains and hills are the best example of the law of superposition. The rock layers are always in contact with each other, specifying that the layers are close in time and the older layer is at the bottom. The contact usually happens for two reasons; first, the younger layer has flowed into the older layer, or the older rocks intruded into, the younger ones.<br /><p></p><p>The law of superposition does not mean that all geologic features can be explained solely by superposition. For example, the folding of the strata in a mountain range will often be explained by the law of folding. Likewise, when looking at the layers of oil shale, there is a law of maximum age that can be explained as a matter of the most recently exposed rock being of the oldest age. However, generally, many geologic structures will be most naturally explained through a combination of the laws of superposition and the law of sedimentary basin development, rather than through the law of superposition alone.<br /><br /><br /></p>

The Principle of Superposition

The law of superposition, states that the sequence of layers observed in sedimentary rocks marks the time of deposition of the layers. The...

The Geology Behind the Deadly Earthquakes in Turkey

Earthquakes, Geology, Tectonic 8:36 PM

<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjD233-jaioWJZlJQO3_ymkilkNsYhLh8YZyEHZH3FGvubr7BtJ1C9cgvLDEAjxoONXwtLoTVDxHWskO5ySB9nXcdFUcQG95dNN5yiOacohQfbYgXKDzsP_brSBKqJCQSesZpI-hgBVSwH-E_M88jrMUP_VHvaDhzuHCRNL4iUqiUWGXfwVZhLSYpmy/s1280/The%20geology%20behind%20the%20deadly%20earthquakes%20in%20Turkey%20and%20Syria.jpg" style="margin-left: auto; margin-right: auto;"><img alt="The Geology Behind the Deadly Earthquakes in Turkey and Syria" border="0" data-original-height="720" data-original-width="1280" height="360" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjD233-jaioWJZlJQO3_ymkilkNsYhLh8YZyEHZH3FGvubr7BtJ1C9cgvLDEAjxoONXwtLoTVDxHWskO5ySB9nXcdFUcQG95dNN5yiOacohQfbYgXKDzsP_brSBKqJCQSesZpI-hgBVSwH-E_M88jrMUP_VHvaDhzuHCRNL4iUqiUWGXfwVZhLSYpmy/w640-h360/The%20geology%20behind%20the%20deadly%20earthquakes%20in%20Turkey%20and%20Syria.jpg" title="The Geology Behind the Deadly Earthquakes in Turkey and Syria" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">The Geology Behind the Deadly Earthquakes in Turkey and Syria<br /></td></tr></tbody></table><p style="text-align: left;"></p><h3 style="text-align: left;">Why Have So Many Earthquakes Hit Turkey and Syria?</h3><p style="text-align: left;">Earthquakes in Syria and Turkey are common, but the magnitude 7.8 that shook the region on 6 February at 4:17am local time is clearly impressive. To find earthquakes this strong on this particular fault, we would have to go back to the year 1114.<br /><br />Ten minutes after the strongest earthquake, an aftershock of magnitude 6.7 struck near the epicentre. “Aftershocks” are earthquakes that occur after every major earthquake, and their statistical behaviour is well known. At the time of writing, others continue to affect an area stretching over 350 kilometres from eastern Turkey to the Syrian border.<br /><br />More surprisingly and dramatically, a second earthquake of magnitude 7.5 struck at 1:24pm local time, further north. This earthquake was not an aftershock: according to the first data processed live by the major international seismological agencies, it would have occurred on an east-west fault crossing-cutting the main rupture trace.<br /><br />Seismologists consider Turkey a tectonically active area, where three tectonic plates—the Anatolia, Arabia, and Africa plates—touch and interact with each other. The two major fault lines surrounding it, the North Anatolian Fault and the East Anatolian Fault—which has a slip rate of between 6 and 10 millimeters per year—are gradually squeezing the country westward toward the Mediterranean Sea. Yet, many buildings in the region are not built to withstand large earthquakes, according to the US Geological Survey (USGS), making the destruction worse. <br /></p><h4 style="text-align: left;"><span style="font-family: georgia;">Plate tectonics</span></h4><p style="text-align: left;">The Anatolian Plate is a continental tectonic plate that is separated from the Eurasian plate and the Arabian plate by the North Anatolian Fault and the East Anatolian Fault respectively. Most of the country of Turkey is located on the Anatolian plate. Most significant earthquakes in the region have historically occurred along the northern fault, such as the 1939 Erzincan earthquake. The devastating 2023 Turkey–Syria earthquake occurred along the active East Anatolian fault at a strike slip fault where the Arabian plate is sliding past the Anatolian plate horizontally.<br /></p><div style="margin: 0px auto; width: 100%;">
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</div><br />The Anatolian transform fault system is "probably the most active in the world".The East Anatolian Fault, a left lateral transform fault, forms a boundary with the Arabian Plate. To the south and southwest is a convergent boundary with the African Plate. This convergence manifests in compressive features within the oceanic crust beneath the Mediterranean as well as within the continental crust of Anatolia itself, and also by what are generally considered to be subduction zones along the Hellenic and Cyprus arcs. The northern edge is a transform boundary with the Eurasian Plate, forming the North Anatolian Fault Zone (NAFZ).<br /><br />Research indicates that the Anatolian Plate is rotating counterclockwise as it is being pushed west by the Arabian Plate, impeded from any northerly movement by the Eurasian Plate. In some references, the Anatolian Plate is referred to as a "block" of continental crust still coupled to the Eurasian Plate. But studies of the North Anatolian Fault indicate that Anatolia is de-coupled from the Eurasian Plate. It is now being squeezed by the Arabian Plate from the east and forced toward the west as the Eurasian Plate to its north is blocking motion in that direction. The African Plate is subducting beneath the Anatolian Plate along the Cyprus and Hellenic Arcs offshore in the Mediterranean Sea.<br /><p></p><h4 style="text-align: left;"><span style="font-family: georgia;">Earthquakes may trigger other earthquakes</span></h4><p style="text-align: left;">An earthquake happens when a fault – a fracture in the first kilometres of the Earth’s crust – slips rapidly, within seconds, abruptly releasing the energy that has been growing over tens to hundreds of years by the slow motion of tectonic plates. When this happens, the released energy leads to shaking of the ground: the earthquake.<br /><br />Some earthquakes are linked to each other: when the fault breaks, earthquakes release part of the energy and reorganise part of it in the Earths’ crust, which can trigger new earthquakes. For instance, one can consider the series of earthquakes of magnitude greater than 7 that have cascaded from east to west for about 800 kilometres over the course of the 20th century along the North Anatolian fault. Each earthquake brought the nearby fault segment of the North Anatolian fault closer to a rupture.<br /><br />The notable point is that the entire length of the North Anatolian Fault ruptured between 1939 and 1999. The last unbroken segment runs across the Sea of Marmara, very close to Istanbul, between the epicenters of the 1999 Izmit and 1912 Ganos earthquakes.<br /><br />If a fault section is already well loaded (close to rupture), when a big earthquake hits nearby, then a second earthquake might happen. Otherwise, it will be necessary to wait for the motion of tectonic plates to bring the remaining energy necessary to trigger an earthquake. This is called “static triggering”.<br /></p><h4 style="text-align: left;"><span style="font-family: georgia;">When giant earthquakes trigger other earthquakes… at a distance</span></h4><p style="text-align: left;">There is also a type of triggering known as “dynamic”. In some cases, the energy excess resulting from a large earthquake is not large enough to explain the occurrence of certain earthquakes, especially if they are located far away from the epicentre of the main shock.<br /><br />For example, following the 1992 Landers and 1999 Hector Mine earthquakes in California, earthquake swarms were observed several hundreds of kilometres from the epicentre. It has been shown that these earthquakes occurred exactly during the passage of the strongest seismic waves emitted by these two earthquakes. At such distances, this shaking, the seismic waves, cannot be felt by humans, but apparently, seismic faults do.<br /><br />Similar observations have been made in the laboratory to show that during the passage of these seismic waves, the material that makes up the core of the fault weakens, causing a sudden sliding, i.e., an earthquake.<br /><br />This kind of behaviour comes from the physics of granular media, which behave like fluids while being shaken. Shaking a pile of sand quickly will cause it to flatten under its own weight, whereas without the shaking, it would stand still.<br /><br />So shaking a fault quickly can cause it to slip, producing earthquakes. It has also been observed that these seismic waves can trigger slow slippage at colossal distances. The seismic waves emitted by the Maule earthquake, a magnitude 8.9 earthquake that struck Chile in 2010, caused a slow earthquake along the Mexico subduction, about 7,000 kilometres from the epicentre.</p><p style="text-align: left;"><br /></p><p style="text-align: left;"><b><a href="https://www.geologyin.com/2023/02/how-turkeys-deadly-earthquake-moved.html" target="_blank">See also: How Turkey's Deadly Earthquake Moved the Country 10 Feet</a></b><br /><br /></p>

The Geology Behind the Deadly Earthquakes in Turkey

The Geology Behind the Deadly Earthquakes in Turkey and Syria Why Have So Many Earthquakes Hit Turkey and Syria? Earthquakes in Syria and Tu...

New Detailed Map Showing the Tectonic Plates With Their Movement Vectors

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Earth News, Geology, Tectonic 9:16 PM

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How Turkey's Deadly Earthquake Moved the Country 10 Feet

Earthquakes, Geology, Tectonic 8:54 PM

<p></p><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvkHBSmNsqsL_oCJCsoxlmVeI7Ex-KCQD7SUcw7ItyoUEleR9qJyKETO506yVupEXCvN1KUjFRbzAtJ6iOMla4idy_v8QQUGRLnmYet60ZA5OMvrkoX4JK4OWi8yd1QA3rGZs73yb_s-UJ0sFMLIml7qDJ68YAsyAuXw6JZmwPiO9uWav1zSaP1ep6/s1206/Turkey%20could%20have%20moved%20three%20metres%20following%20catastrophic%20earthquake%20(1).jpeg" style="margin-left: auto; margin-right: auto;"><img alt="How Turkey's Deadly Earthquake Moved the Country 10 Feet" border="0" data-original-height="835" data-original-width="1206" height="444" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvkHBSmNsqsL_oCJCsoxlmVeI7Ex-KCQD7SUcw7ItyoUEleR9qJyKETO506yVupEXCvN1KUjFRbzAtJ6iOMla4idy_v8QQUGRLnmYet60ZA5OMvrkoX4JK4OWi8yd1QA3rGZs73yb_s-UJ0sFMLIml7qDJ68YAsyAuXw6JZmwPiO9uWav1zSaP1ep6/w640-h444/Turkey%20could%20have%20moved%20three%20metres%20following%20catastrophic%20earthquake%20(1).jpeg" title="How Turkey's Deadly Earthquake Moved the Country 10 Feet" width="640" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">How Turkey's Deadly Earthquake Moved the Country 10 Feet</td></tr></tbody></table><br /><span style="font-family: georgia;"> Turkey could have moved three metres following catastrophic earthquake, expert claims</span><br /><p></p><p>The catastrophic earthquake that has killed thousands across Turkey and Syria has led to the earth moving three metres in its wake, an expert has said.<br /><br />The 7.8 magnitude earthquake struck a large area of southern Turkey and part of northern Syria in the early hours of Monday morning (6 February).<br /><br />Officials have said that more than 4,300 people have died across the two countries, with the Turkish Emergency and Disaster Management Organization (AFAD) confirming there have been 2,291 fatalities in Turkey, along with 15,834 people sustaining injuries in the disaster.<br /><br />There has also been widespread destruction to homes, buildings and roads, while an Italian seismology expert said the ground itself has moved significantly after the deadly quake.<br /><br />Professor Carlo Doglioni, president of the Italian National Institute of Geophysics and Volcanology, told Italian newspaper Corriere Della Sera: “What we call the Arabian plate moved about 3 meters along the northeast-southwest direction relative to the Anatolian plate.<br /></p><div style="margin: 0px auto; width: 100%;">
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</div><br />“We are talking about a structure in the border region between this world, that of the Arabian plate and that of the Anatolian plate.”<br /><br />The area sits on several fault lines, meaning it is frequently struck by earthquakes.<br /><br />According to the US Geological Survey, this week’s was centred about 33 kilometres from the Turkish city of Gaziantep, in the region of Anatolia.<br /><br />Doglioni added: “We are talking about continuous movement, the plane of the fault is very inclined and during the event we observe a horizontal displacement of the two sides of the fault. The two fins moved relative to each other.<br /><br />“In other words: it is as if Turkey had moved in relation to the Arabian plate to the southwest.”<br /><br />Authorities have urged people to stay off the roads, with mosques in the area opened up to offer shelter to those who cannot return to their homes but who need to get out of the cold.<br /><br />'The faults that slipped yesterday in Turkey are strike-slip faults that involve mainly horizontal displacements, and so the overall offsets in the region of 3 to 6 metres proposed here are perfectly reasonable.<br /><br />'Horizontal offsets of this kind can lead to the severing of major subsurface and surface infrastructure, including water mains, electricity cables, gas pipelines and tunnels. <br /><br />'There may also be surface ruptures developed where the faults break through to the surface – these can offset roads, rivers and other features – including built structures.  'All this is in addition to the damage caused by shaking, liquefaction of soft sediment in valleys/basins and landslides.' <br /><br />Catastrophic earthquakes are caused when two tectonic plates that are sliding in opposite directions stick and then slip suddenly. <br /><br />They are composed of Earth's crust and the uppermost portion of the mantle, while below is the asthenosphere, the warm, viscous conveyor belt of rock on which tectonic plates ride.<br /><br />They do not all move in the same direction and often clash, which builds up a huge amount of pressure between the two plates. Eventually, this pressure causes one plate to jolt either under or over the other. <br /><br />This releases a huge amount of energy, creating tremors and destruction to any property or infrastructure nearby. Severe earthquakes normally occur over fault lines where tectonic plates meet, but minor tremors – which still register on the Richter sale – can happen in the middle of these plates. <br /><br />Turkey is close to the intersection of three tectonic plates, meaning it is prone to earthquakes. Dr Anastasios Sextos, a professor of earthquake engineering at the University of Bristol, said: 'The area of Aleppo and Gazientep have experienced a series of historically devastating earthquakes and an event of similar magnitude occurred about two centuries ago.'<br /><br />The majority of Turkey's landmass sits on the Anatolian Plate, which is being squeezed between three other large plates.<br /><br />North of the plate is the Eurasian Plate, south is the African Plate and to the east lies the Arabian Plate. These create two large faultlines – the East Anatolian and North Anatolian – which are both prone to seismic activity.<br /><br />This is because the Arabian plate pushes northwards into the Eurasian plate, squeezing the Anatolian Plate westwards towards the Aegean Sea.<br /><br />Monday's earthquakes occurred on the southwest end of the 434 mile-long (699 km) East Anatolian faultline.<br /><br />The first 7.8-magnitude quake was at a depth of about 11 miles (18 km), while the second occurred nine hours later at a depth of six miles (10 km) and a 7.5-magnitude.<br /><br />Dr Joanna Faure Walker, professor of earthquake geology and disaster risk reduction at University College London (UCL), said that these were both 'strike-slip' earthquakes.<br /><br />This is where two blocks of land move horizontally along a fault plane as a result of a build-up of stress from horizontal compression. 'Strike-slip faults have medium strength, so can host earthquakes up to magnitude 7 or 8. <br /><br />'The magnitude is dependent on the slip and length of fault that ruptured. <br /><br />'So for a fault system that is 690 kilometres long in total, such large magnitude earthquakes are possible.'<br /><br />The East Anatolian has a slip rate of between 0.2 and 0.4 inches (6 and 10 mm) a year near eastern Turkey.<br /><br />However, data shared by meteorologist Matthew Cappucci, from MyRadar Weather, shows that this week's quakes have caused the Anatolian Plate to slide by up to 10 feet (three metres).<br /><br />Dr Doglioni added that more data from the European Sapce Agency's Sentinel and ASI CosmoSkymed satellites would provide more information in the next few days.<br /><br />According to Dr David Rothery, a geoscientist at the Open University, Turkey moves about 0.8 inches (two centimetres) west per year along the East Anatolian fault.<br /><br />He said:  'Because of friction along fault lines, the motion is not smooth. <br /><br />'Instead strain builds up locally over years or decades until the accumulated stress is strong enough to overcome resistance and rock masses snap past each other in a sudden jerk.<br /><br />'In this case, the violence of the shaking at the surface has been strong enough to make buildings collapse, which is probably how most lives have been lost. There may have been landslides too in hilly terrain.'<br /><br /><p></p>

How Turkey's Deadly Earthquake Moved the Country 10 Feet

How Turkey's Deadly Earthquake Moved the Country 10 Feet Turkey could have moved three metres following catastrophic earthquake, expert...

225-MillionYear-Old Petrified Opal Tree Trunk Located in Arizona

Fossils, places to visit 8:02 PM

<p></p>Petrified wood found in the park and the surrounding region is made up of almost solid quartz. Each piece is like a giant crystal, often sparkling in the sunlight as if covered by glitter. The rainbow of colors is produced by impurities in the quartz, such as iron, carbon, and manganese.<br /><br /><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXKAwGsrf49seAfY9aDB1SlaRvZT0fFUSLBKhI1EdYq-cmiKgtR95Zke6af_HzFEBDKOQmvS9_ri1Dq8krKdy4mNcOieaQjwq-lx8IFqI2nitALB3_bH66sAPq2koWr9nra0caArNOWNUTsluG4bdHr3XZ13ngt3PiecCgPm4OHFD9lokOQLU4Td0K/s1152/Opalized%20Petrified%20Wood%20(1).jpg" style="margin-left: auto; margin-right: auto;"><img alt="225-MillionYear-Old Petrified Opal Tree Trunk Located in Arizona" border="0" data-original-height="1152" data-original-width="1152" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXKAwGsrf49seAfY9aDB1SlaRvZT0fFUSLBKhI1EdYq-cmiKgtR95Zke6af_HzFEBDKOQmvS9_ri1Dq8krKdy4mNcOieaQjwq-lx8IFqI2nitALB3_bH66sAPq2koWr9nra0caArNOWNUTsluG4bdHr3XZ13ngt3PiecCgPm4OHFD9lokOQLU4Td0K/w400-h400/Opalized%20Petrified%20Wood%20(1).jpg" title="225-MillionYear-Old Petrified Opal Tree Trunk Located in Arizona" width="400" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">225-MillionYear-Old
 Petrified Opal Tree Trunk Located in Arizona. Colorful crystal patterns
 are displayed in a cross-section of petrified
wood in the Petrified Forest National Park, located in northeast
Arizona.<b> <a href="https://www.instagram.com/patrickakabird/" rel="nofollow" target="_blank">Photo by: Patrick Fuchs</a></b></td></tr></tbody></table><p>Over 200 million years ago, the logs washed into an ancient river system and were buried quick enough and deep enough by massive amounts of sediment and debris also carried in the water, that oxygen was cut off and decay slowed to a process that would now take centuries.</p><p></p><div style="margin: 0px auto; width: 100%;">
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</div><br /><p></p><p></p><p>Petrified wood forms when woody stems of plants are buried in wet sediments saturated with dissolved minerals. The lack of oxygen slows decay of the wood, allowing minerals to replace cell walls and to fill void spaces in the wood.<br /><br />Minerals, including silica dissolved from volcanic ash, absorbed into the porous wood over hundreds and thousands of years crystallized within the cellular structure, replacing the organic material as it broke down over time. Sometimes crushing or decay left cracks in the logs. <br /></p><p>Most of the color in petrified wood comes from trace metals. Of these, iron is the most important, and it can produce a range of hues depending on its oxidation state. Chromium produces bright green petrified wood. Variations in color likely reflect different episodes of mineralization. In some cases, variations may come from chromatographic separation of trace metals.<br /></p><p>Some 40 minerals have been identified in petrified wood, but silica minerals are by far the most important. Calcite and pyrite are much less common, and others are quite rare. Silica binds to the cellulose in cell walls via hydrogen bonding and forms a kind of template. Additional silica then replaces the cellulose as it decomposes, so that cell walls are often preserved in great detail.<br /></p><p><br /></p>

225-MillionYear-Old Petrified Opal Tree Trunk Located in Arizona

Petrified wood found in the park and the surrounding region is made up of almost solid quartz. Each piece is like a giant crystal, often spa...

Geology In