Geology In

What Happens Under the Yellowstone Volcano?

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The Yellowstone National Park in the USA with its geysers and hot springs is a great attraction for tourists. However, especially in times of little news, the media often focusses on the Yellowstone Supervolcano, which last erupted about 630,000 years ago. <br />
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Inevitably, then the question of the underlying geological structures will be posed. A recent study by Bernhard Steinberger of the German GeoForschungsZentrum and colleagues in the USA helps to better understand the processes in the Earth's interior. The paper will soon appear in the journal "Geochemistry, Geophysics, Geosystems" published by the American Geophysical Union. It is based on modelling the Earth's mantle.<br />
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According to the model, beneath the Yellowstone volcano lies a so-called mantle plume: a chimney-like structure that reaches thousands of kilometres deep to the border of the Earth's core and mantle. The origin of the plume lies under the "Baja California," more than a thousand kilometers southwest of the national park. Evaluations of earthquake waves had already suggested something like this, but the idea of such a "mantle plume" did not fit in with the movement of the Earth's lithospheric plates.<br />
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It is clear that Yellowstone is a so-called intraplate volcano. Most volcanoes in the world are located at the borders of continental plates, either where material from the Earth's interior rises, as in Iceland, or where one continental plate submerges under the other and melts, as is the case along the American westcoast.<br />
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In contrast to plate boundary volcanism, intraplate volcanism goes back to "hotspots" under the Earth's crust. This can be imagined as a welding torch that melts the lithosphere from below -- where a hole is virtually burned through, a volcano grows. This is how Hawaii, for example, came into being.<br />
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The seismic data for Yellowstone, however, did not provide a clear picture for a long time. This has changed due to new data and refined measurement methods, which have allowed the deeper part of the plume to be imaged in a tomographic image. However, gaps remain in the upper mantle. <br />
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The data were not so clear here. The study from the GFZ now fills these gaps with a modelling result that maps the mantle plume consistently with the observation data. Accordingly, there are slow movements of the rock in the lower mantle of the Earth, which are directed southwest relative to the surface.<br />
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Like the plume of smoke of a steam ship, the mantle plume moves from Baja California to the north-northeast to the Yellowstone volcano. Bernhard Steinberger: "Our study contributes to a better understanding of intraplate volcanism and supports the hypothesis of a deep mantle plume. However, this has no impact on the risk assessment of the Yellowstone volcano."<br />
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<i><u><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.gfz-potsdam.de/en/media-and-communication/news/details/article/what-happens-under-the-yellowstone-volcano/" rel="nofollow" target="_blank">Materials</a> provided by <a href="https://www.gfz-potsdam.de/en/home/" rel="nofollow" target="_blank">GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre</a>.</span></u></i></div>

What Happens Under the Yellowstone Volcano?

The Yellowstone National Park in the USA with its geysers and hot springs is a great attraction for tourists. However, especially in t...

The Mystery of the Giant Crystals: How the 36-foot Geode of Pulpí Formed

caves, places to visit, Researches 7:00 PM

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<tr><td class="tr-caption" style="text-align: center;">This is the geode of Pulpí.. Credit: Javier Trueba/MSF/Science Source</td></tr>
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<b><span style="font-family: "georgia" , "times new roman" , serif;">The Giant Geode of Pulpí – Unlocking the Mystery of the Giant Crystals</span></b><br />
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This incredible natural space is the Geode of Pulpí, the closest 
thing in real life to Superman's Fortress of Solitude: an amazing 
egg-shaped cavern where jagged shards of brilliant, clear crystal jut 
from the walls like teeth in a dragon's mouth.<br />
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The geode of Pulpí is an 11-meter hollow ovoid with crystal-paneled walls. It is like those familiar couplets of stone interiors covered with bright crystallites, but so large that several people can fit inside. The crystals, of up to two meters in size, are so transparent that they look like ice crystals. In this paper for Geology, Juan Manuel García-Ruiz and colleagues reveal the geological history that ended with the formation of the Pulpí geode.<br />
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As far as geodes go, Pulpí's is a giant – one of the largest known geodes in the world in fact.<br />
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In terms of cavernous chambers, though, it's actually tiny, but is large enough that multiple people can fit inside it at once, which isn't something you can say about most geode cavities.<br />
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Like the giant crystals of Naica in Mexico, the crystals of Pulpí are gypsum (calcium sulfate with two water molecules). García-Ruiz says, “To reveal their formation has been a very tough task because unlike in the case of Naica, where the hydrothermal system is still active, the large geode of Pulpí is a fossilized environment.”<br />
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The team performed a study of the geology and geochemistry of the abandoned mine where the geode was found, including a detailed mapping of the underground mining works, which has been used to allow the tourist visits in the mine.<br />
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They found that the crystals of Pulpi formed at around 20 °C, at a shallow depth where the temperature fluctuations of the climate are still perceptible. These temperature fluctuations, being below the maximum solubility of gypsum (40 °C), led to the dissolution and recrystallization amplifying a maturation process that is known as Ostwald maturation.<br />
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Says García-Ruiz, "This is somewhat like the temperature cycles in crystal quality control in industrial processes." A continuous supply of salt for the formation of the crystals was provided by the dissolution of anhydrite (the anhydrous form of calcium sulfate), the mechanism accounting for the formation of the large crystals of Naica.<br />
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Because of their purity, the crystals forming the geode cannot be dated precisely. But indirect constraint can be done: "They grew for sure after the desiccation of the Mediterranean Sea that occurred 5.6 million years ago. They are most probably younger than two million years but older than 60.000 years because this is the age of the carbonate crust coating one of the large gypsum crystal," says García-Ruiz.<br />
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<tr><td class="tr-caption" style="text-align: center;">Credit: Javier Trueba/MSF/Science Source</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">See also: </span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="http://www.geologyin.com/2016/02/the-rainbow-mountains-in-peru-very.html" target="_blank">The Rainbow Mountains in Peru very Amazing</a></span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a class="OYKEW4D-e-i" href="http://www.geologyin.com/2014/11/the-huge-cave-mines-at-naica-mexico.html" target="_blank">Cave of Crystals "Giant Crystal Cave" at Naica, Mexico</a> </span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><br /></span>
<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://pubs.geoscienceworld.org/gsa/geology/article/574380/The-origin-of-large-gypsum-crystals-in-the-Geode" rel="nofollow" target="_blank">materials </a>provided by<a href="https://www.geosociety.org/" rel="nofollow" target="_blank"> Geological Society Of America.</a></span></i></u></div>

The Mystery of the Giant Crystals: How the 36-foot Geode of Pulpí Formed

This is the geode of Pulpí.. Credit: Javier Trueba/MSF/Science Source The Giant Geode of Pulpí – Unlocking the Mystery of the Giant Cr...

Trilobite Fossils Show Conga Line Frozen for 480 Million Years

Earth History, extinction, Fossils 6:55 PM

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<tr><td class="tr-caption" style="text-align: center;">Ampyx priscus in linear formation (Moroccan Lower Ordovician Fezouata Shale). Credit: Jean Vannier, Laboratoire de Geologie de Lyon: Terre, Planètes, Environnement (CNRS / ENS de Lyon / Université Claude Bernard Lyon 1)</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">Arthropod fossils dating back 500million years show the creatures died in an orderly line 'while migrating'</span></h4>
Fossils of ancient arthropods discovered in linear formation may indicate a collective behaviour either in response to environmental cues or as part of seasonal reproductive migration. The findings, which are being published in Scientific Reports this week, suggest that group behaviours comparable to those of modern animals existed as early as 480 million years ago.<br />
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Collective and social behaviour is known to have evolved through natural selection over millions of years and modern arthropods provide numerous examples, such as the migratory chains of caterpillars, ants or spiny lobsters. Yet, the origins and early history of collective behaviour has remained largely unknown.<br />
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Jean Vannier and colleagues described several linear clusters of Ampyx priscus, a trilobite arthropod from the lower Ordovician period (ca 480 Million years ago) of Morocco. The trilobites, which were between 16 and 22 millimetres long, had a stout spine at the front of their bodies and a pair of very long spines at the back. In each cluster of trilobite fossils examined by the authors, individuals were arranged in a line, with the front of their bodies facing in the same direction, maintaining contact via their spines. <br />
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The authors suggest that, given the scale of the patterns seen, this consistent linearity and directionality is unlikely to be the result of passive transportation or accumulation by currents. Instead, it is more likely that Ampyx was killed suddenly while travelling, for example by being buried rapidly by sediment during a storm.<br />
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The authors suggest that Ampyx probably migrated in groups and used their long projecting spines to maintain a single-row formation by physical contact, as they moved along the seafloor. This may have been a stress response to disturbance of their environment by storms, detected by motion and touch sensors, which motivated Ampyx to migrate to quieter and deeper waters. <br />
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A comparable behaviour is seen in present-day spiny lobsters. Alternatively, the pattern may have been the result of a seasonal reproductive behaviour involving the migration of sexually mature individuals to spawning grounds. Knowing that Ampyx was blind, the authors hypothesize that the trilobites may have coordinated using sensory stimulation via spines and chemicals.<br />
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The discovery shows that a 480-million-year-old arthropod may have used its neural complexity to develop a temporary collective behaviour.<br />
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<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://www.nature.com/articles/s41598-019-51012-3" rel="nofollow" target="_blank">materials </a>provided by <a href="https://www.universite-lyon.fr/version-anglaise/the-universite-de-lyon-is-a-world-class-academic-site-of-excellence-6709.kjsp" rel="nofollow" target="_blank">The University of Lyon</a>.</span></i></u></div>

Trilobite Fossils Show Conga Line Frozen for 480 Million Years

Ampyx priscus in linear formation (Moroccan Lower Ordovician Fezouata Shale). Credit: Jean Vannier, Laboratoire de Geologie de Lyon: Te...

Crystal Habits and Forms

Geochemistry, Mineral, Mineralogy 7:42 PM

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The term crystal habit describes the favored growth pattern of the crystals of a mineral species, whether individually or in aggregate. It may bear little relation to the form of a single, perfect crystal of the same mineral, which would be classified according to crystal system. Subtle evidence of the crystal system to which a mineral species belongs is, however, frequently observed in the habit of the crystals which a specimen displays.<br />
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The terminology used to describe crystal habit is not intended to replace the precise nomenclature of crystallography. Instead, it is intended as a supplement to this system.<br />
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Discussions of crystal habit are more descriptive than precise; for this reason the terminology is suited to the discussion of mineral samples discovered in the field. Naturally formed specimens are rarely quantitatively perfect.<br />
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<tr><td class="tr-caption" style="text-align: center;">Scalenohedron Calcite on Dolomite from the Elmwood Mine in Tennessee  <br />
Photo: Alex Crystallize</td></tr>
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<span style="font-family: "georgia" , "times new roman" , serif;">The crystals of particular minerals species sometimes form very distinctive, characteristic shapes. Crystal habit is thus often useful in identification.</span><br />
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Although each mineral species typically forms according to a few preferred shapes, crystal habit is largely determined by the environmental conditions under which a crystal develops. For example, aqueous solutions near or surrounding a crystal contain the elemental substances which it needs to continue growth.<br />
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The direction from which a growing crystal may obtain such solutions is a factor which will affect its eventual shape. Higher environmental temperatures during formation increase ion mobility and aid in crystal formation; the rate at which the environment cools determines how much time a mineral is allowed to form large crystals. The amount of space available for a crystal to fill affects its final shape and size.<br />
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</div><span style="font-family: "georgia" , "times new roman" , serif;">Surface energy relations are also quite important to the direction of crystal growth; this process is not yet fully understood.</span><br />
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<b>Adjectives </b>used to describe the habit of individual crystals are 'equant,' 'prismatic,' and 'tabular.' Aggregates of crystals may also be termed equant or prismatic, while aggregates of thin, flat, tabular crystals may be 'bladed.' Thin sheets, flakes or scales are termed 'foliated,' 'micaceous,' and, if feathery or delicate, 'lamellar' or 'plumose.'<br />
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Crystal aggregates resembling long, slender needles, hair, or thread are termed 'acicular,' filiform,' 'capillary,' or 'fibrous.' An aggregate of crystals forming a network or lattice is 'reticulated;' one composed of branches which radiate starlike from a central point is 'stellated' while a branching and treelike mineral growth is 'dendritic.'<br />
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'Colloform' crystal habits termed 'botryoidal,' 'mamillary,' and 'reniform' display spherical, bulbous or globular lumps. Smaller spherical forms are of 'pisolitic' or 'oolitic' habit; ovoid clusters or formations are 'amygdaloidal.'<br />
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Tapered, column-like formations are 'stalactitic' or 'columnar' while concentrically banded formations are of 'concretionary' habit. Minerals whose flat crystal faces are covered with shallow, parallel grooves are 'striated;' a fine furry layer of crystals growing over a massive lump constitutes a formation of 'drusy' habit.<br />
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Following is a list of descriptive terms which are applied when discussing crystal habit.</span></b><br />
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Equant</span></b><br />
A crystal which is equant or equidimensional possesses approximately the same side length in every direction. Crystals of garnet are often of equant habit.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-GffOtfWrZM4/XaXknpEIkZI/AAAAAAAARh8/TWkPXxde3CcN-WVuYy7jJwSlsplLVTgSwCLcBGAsYHQ/s1600/Prismatic%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="500" data-original-width="282" height="320" src="https://1.bp.blogspot.com/-GffOtfWrZM4/XaXknpEIkZI/AAAAAAAARh8/TWkPXxde3CcN-WVuYy7jJwSlsplLVTgSwCLcBGAsYHQ/s320/Prismatic%2B%25281%2529.jpg" width="180" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Prismatic Calcite. Photo: Irocks.com</td></tr>
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Prismatic</span></b><br />
A prismatic crystal is elongated in one direction like a prism. The mineral tourmaline often forms crystals of such habit.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-eGjyLSKNj6o/XaXiTFXdxEI/AAAAAAAARho/ObEq0P2_9xgr0Aa5uLGItd_yN0xjRGlHgCLcBGAsYHQ/s1600/Tabular%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="556" data-original-width="637" height="279" src="https://1.bp.blogspot.com/-eGjyLSKNj6o/XaXiTFXdxEI/AAAAAAAARho/ObEq0P2_9xgr0Aa5uLGItd_yN0xjRGlHgCLcBGAsYHQ/s320/Tabular%2B%25281%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Tabular vanadanite.  Photo: Weinrich Minerals, Inc</td></tr>
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Tabular</span></b><br />
Tabular crystals appear tabular or platelike in shape.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-CbdQa2N524o/XaXi1KAB4pI/AAAAAAAARhw/nkAsMh3sfCQvR9b6mxaGo_Lcv24s0hp0ACLcBGAsYHQ/s1600/Bladed%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="449" data-original-width="605" height="237" src="https://1.bp.blogspot.com/-CbdQa2N524o/XaXi1KAB4pI/AAAAAAAARhw/nkAsMh3sfCQvR9b6mxaGo_Lcv24s0hp0ACLcBGAsYHQ/s320/Bladed%2B%25281%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Bladed calcite. Photo: viamineralia.com</td></tr>
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Bladed</span></b><br />
A specimen displaying bladed habit possesses a collection of elongated, flat crystals suggestive of knife blades. Gypsum often displays crystals of bladed habit.<br />
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</div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-RPSKhUBS1rI/XaXcgYb3BSI/AAAAAAAARgc/VTeifOnMd34VJ_VpNsMOVZIANwmSa0fiQCLcBGAsYHQ/s1600/Micaceous.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="389" data-original-width="535" height="232" src="https://1.bp.blogspot.com/-RPSKhUBS1rI/XaXcgYb3BSI/AAAAAAAARgc/VTeifOnMd34VJ_VpNsMOVZIANwmSa0fiQCLcBGAsYHQ/s320/Micaceous.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span data-offset-key="6mbm4-0-0"><span data-text="true">Micaceous Muscovite </span></span></td></tr>
</tbody></table><br />
<b><span style="font-family: "georgia" , "times new roman" , serif;">Micaceous</span></b><br />
Minerals of micaceous habit form as thin, flat sheets or flakes which are easily peeled or split off the larger mass. Muscovite provides an example of micaceous habit. Crystals of foliated habit are separable into leafy structures or display leaflike projections.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-nrT2eYCNO3c/XaXlgeRxVlI/AAAAAAAARiE/UkLd_100EBcsnX8tmjtlzOTxPrZisw4pgCLcBGAsYHQ/s1600/Hopper%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="766" data-original-width="600" height="320" src="https://1.bp.blogspot.com/-nrT2eYCNO3c/XaXlgeRxVlI/AAAAAAAARiE/UkLd_100EBcsnX8tmjtlzOTxPrZisw4pgCLcBGAsYHQ/s320/Hopper%2B%25281%2529.jpg" width="250" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Hopper halite. Photo: Spirifer Minerals</td></tr>
</tbody></table><br />
<b><span style="font-family: "georgia" , "times new roman" , serif;">Hopper </span></b><br />
<div class="separator" style="clear: both; text-align: center;"></div>A hopper crystal is a form of crystal, defined by its "hoppered" shape. The edges of hoppered crystals are fully developed, but the interior spaces are not filled in. This results in what appears to be a hollowed out step lattice formation, as if someone had removed interior sections of the individual crystals. In fact, the "removed" sections never filled in, because the crystal was growing so rapidly that there was not enough time (or material) to fill in the gaps.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-OAVdIoR9l5U/XaX1ioSvUeI/AAAAAAAARjY/FRYdX8Bixh0iBmjlug5Zn-abYhiUniOvACLcBGAsYHQ/s1600/Plumose%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="605" data-original-width="602" height="320" src="https://1.bp.blogspot.com/-OAVdIoR9l5U/XaX1ioSvUeI/AAAAAAAARjY/FRYdX8Bixh0iBmjlug5Zn-abYhiUniOvACLcBGAsYHQ/s320/Plumose%2B%25281%2529.jpg" width="318" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Plumose Aurichalcite. Photo: Rob Lavinsky</td></tr>
</tbody></table><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><b><span style="font-family: "georgia" , "times new roman" , serif;">Plumose</span></b><br />
<div class="separator" style="clear: both; text-align: center;"></div><b><span style="font-family: "georgia" , "times new roman" , serif;"> </span></b> A mineral specimen of plumose habit displays fine, feathery scales resembling plumes. 'Plumose' is derived from the Latin term pluma, or 'feather.'<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-fgjJvTmJSlQ/XaXhscbKzcI/AAAAAAAARhg/NVNv-B_AE30hNeHZaXRAD72KMT-Qa_SHACLcBGAsYHQ/s1600/Acicular%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="489" data-original-width="604" height="259" src="https://1.bp.blogspot.com/-fgjJvTmJSlQ/XaXhscbKzcI/AAAAAAAARhg/NVNv-B_AE30hNeHZaXRAD72KMT-Qa_SHACLcBGAsYHQ/s320/Acicular%2B%25281%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"> Acicular agardite-Ce.  Photo: Joy Desor Mineralanalytik</td></tr>
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<div class="separator" style="clear: both; text-align: center;"></div><b><span style="font-family: "georgia" , "times new roman" , serif;">Acicular</span></b><br />
<div class="separator" style="clear: both; text-align: center;"></div><b><span style="font-family: "georgia" , "times new roman" , serif;"> </span></b> The adjective 'acicular' means needlelike in shape. An acicular aggregate of crystals contains many long, slender crystals which may radiate out like needles or bristles from a common base. Acicular crystals are typically long and narrow like a pine leaf and seem to possess a sharp point. The mineral natrolite often exhibits acicular crystals.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-3kEEHIM9adA/XaXwdMQoyCI/AAAAAAAARi8/mTetiJlTpGcT4MhMHSJkduINOk1xAxL5QCLcBGAsYHQ/s1600/Filiform%2BMalachite.%2BPhoto%2BSandro%2BBonfiglio%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="401" data-original-width="605" height="212" src="https://1.bp.blogspot.com/-3kEEHIM9adA/XaXwdMQoyCI/AAAAAAAARi8/mTetiJlTpGcT4MhMHSJkduINOk1xAxL5QCLcBGAsYHQ/s320/Filiform%2BMalachite.%2BPhoto%2BSandro%2BBonfiglio%2B%25281%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Filiform Malachite. Photo: Sandro Bonfiglio</td></tr>
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Filiform</span></b><br />
A mineral possessing crystals of filliform habit exhibits many hairlike or threadlike filaments. "Filiform' is derived from the Latin word filum, 'thread.'<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-FAgUtWULTwk/XaXhMyFFZuI/AAAAAAAARhY/oP6StOZh8pUozSKrd37dH8qhE3jpiR3qACLcBGAsYHQ/s1600/Fibrous%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="682" data-original-width="682" height="320" src="https://1.bp.blogspot.com/-FAgUtWULTwk/XaXhMyFFZuI/AAAAAAAARhY/oP6StOZh8pUozSKrd37dH8qhE3jpiR3qACLcBGAsYHQ/s320/Fibrous%2B%25281%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Fibrous Scolecite. Photo: Matrix India</td></tr>
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</div><b><span style="font-family: "georgia" , "times new roman" , serif;">Fibrous</span></b><br />
Specimens possessing fibrous habit exhibit clumps of sinewy, stringy, or hairlike fibers.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-49pynZMc67k/XaShRiRInSI/AAAAAAAARgQ/ecoaFCR09Fc8mv9AHFNK6b2px865WEeIQCLcBGAsYHQ/s1600/CERUSSITE%2B%2528RETICULATED%2BHABIT%25292.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="435" data-original-width="607" height="229" src="https://1.bp.blogspot.com/-49pynZMc67k/XaShRiRInSI/AAAAAAAARgQ/ecoaFCR09Fc8mv9AHFNK6b2px865WEeIQCLcBGAsYHQ/s320/CERUSSITE%2B%2528RETICULATED%2BHABIT%25292.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Cerussite (Reticulated Habit). Photo: Crystal Classics </td></tr>
</tbody></table><b><span style="font-family: "georgia" , "times new roman" , serif;">Reticulated</span></b><br />
A mineral specimen of reticulated habit seems to display a lattice, net, or network of small crystals. The word 'reticulated' is derived from the Latin term rete, or 'net.'<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-K5KPCJ-FTdQ/XaXzvcnkmYI/AAAAAAAARjI/J-sDijW0W_onnvdWHq1aiR-1jajg_asPgCLcBGAsYHQ/s1600/Wavellite%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="618" data-original-width="564" height="320" src="https://1.bp.blogspot.com/-K5KPCJ-FTdQ/XaXzvcnkmYI/AAAAAAAARjI/J-sDijW0W_onnvdWHq1aiR-1jajg_asPgCLcBGAsYHQ/s320/Wavellite%2B%25281%2529.jpg" width="292" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Stellated Wavellite. Photo: FenderMinerals</td></tr>
</tbody></table><b><span style="font-family: "georgia" , "times new roman" , serif;">Stellated</span></b><br />
A mineral of stellated habit possesses several branches which radiate outwards from the center in a pattern resembling a star. The word 'stellated' stems from the Latin term stella, or 'star.'<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-6yIs8YJ_V8g/XaXeKrm8U_I/AAAAAAAARgs/eUXGGKB7-ccfrxPdvS6ZCiFKIRqHqPEbQCLcBGAsYHQ/s1600/Dendritic%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Dendritic Pyrolusite " border="0" data-original-height="411" data-original-width="608" height="216" src="https://1.bp.blogspot.com/-6yIs8YJ_V8g/XaXeKrm8U_I/AAAAAAAARgs/eUXGGKB7-ccfrxPdvS6ZCiFKIRqHqPEbQCLcBGAsYHQ/s320/Dendritic%2B%25281%2529.jpg" title="" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Dendritic Pyrolusite </td></tr>
</tbody></table><br />
<b><span style="font-family: "georgia" , "times new roman" , serif;">Dendritic</span></b><br />
Dendritic crystals form a divergent branching structure reminiscent of an arborescent, organic growth such as a tree or a dendrite. Native copper sometimes exhibits this habit.<br />
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Colloform</span></b><br />
Specimens of colloform habit exhibit spherical, rounded, or bulbous shapes. Botryoidal, reniform, and mammillary habits are subsets of this category.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-YqSHTptUCOE/XaXgp5boNuI/AAAAAAAARhQ/mErJ5UhdoWodljdvzeV-0rjA5HGB4jmpACLcBGAsYHQ/s1600/Botryoidal%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="548" data-original-width="601" height="291" src="https://1.bp.blogspot.com/-YqSHTptUCOE/XaXgp5boNuI/AAAAAAAARhQ/mErJ5UhdoWodljdvzeV-0rjA5HGB4jmpACLcBGAsYHQ/s320/Botryoidal%2B%25281%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">botryoidal Agate</td></tr>
</tbody></table><b><span style="font-family: "georgia" , "times new roman" , serif;">Botryoidal</span></b><br />
<div class="separator" style="clear: both; text-align: center;"></div>The word 'botryoidal' means 'resembling a bunch of grapes,' or globular. Specimens of malachite frequently provide examples of botryoidal crystals. The Greek word botrus, 'bunch of grapes,' provides the linguistic root of botryoidal.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-jq1zGaoWIWo/XaXtQwH2iEI/AAAAAAAARiw/PBFKRtSHCggW2k2pYvBwFPvJ7fxy-2hNwCLcBGAsYHQ/s1600/Mammillary%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="499" data-original-width="604" height="264" src="https://1.bp.blogspot.com/-jq1zGaoWIWo/XaXtQwH2iEI/AAAAAAAARiw/PBFKRtSHCggW2k2pYvBwFPvJ7fxy-2hNwCLcBGAsYHQ/s320/Mammillary%2B%25281%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Mammillary Erythrite. </td></tr>
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</div><b><span style="font-family: "georgia" , "times new roman" , serif;">Mammillary</span></b><br />
Samples possessing mammillary crystal habit display soft, rounded curves.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-NAzayc91f-w/XaXfAV9wlPI/AAAAAAAARg4/ztX7h5p20xwpigtXZwFTSE9scsfumXSoACLcBGAsYHQ/s1600/Reniform%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="529" data-original-width="633" height="267" src="https://1.bp.blogspot.com/-NAzayc91f-w/XaXfAV9wlPI/AAAAAAAARg4/ztX7h5p20xwpigtXZwFTSE9scsfumXSoACLcBGAsYHQ/s320/Reniform%2B%25281%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Reniform Hematite. Photo: Irocks.com</td></tr>
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Reniform</span></b><br />
Reniform crystal habit displays the shape of a kidney. The mineral species hematite provides samples which exemplify both mammillary and reniform habit. 'Reniform' is derived from the Latin renes, 'kidney.'<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-0sTToxsg4vw/XaXnqmmJvKI/AAAAAAAARiQ/TbIYBoc7d8oKtCqRLcMyvQLSHLBUHNnJQCLcBGAsYHQ/s1600/Oolitic%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="425" data-original-width="608" height="223" src="https://1.bp.blogspot.com/-0sTToxsg4vw/XaXnqmmJvKI/AAAAAAAARiQ/TbIYBoc7d8oKtCqRLcMyvQLSHLBUHNnJQCLcBGAsYHQ/s320/Oolitic%2B%25281%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Oolitic Calcite. Photo: James St. John</td></tr>
</tbody></table><b><span style="font-family: "georgia" , "times new roman" , serif;">Oolitic</span></b><br />
Crystals of oolitic habit form small spheres or grains which resemble fish roe. Oolites are often found in limestones.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-yZO8ZtGOLM8/XaXoSPCVOJI/AAAAAAAARiY/S-BuCAFAxoMssyId1jiDMQp0fRbzsfR3ACLcBGAsYHQ/s1600/Pisolitic%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="490" data-original-width="602" height="260" src="https://1.bp.blogspot.com/-yZO8ZtGOLM8/XaXoSPCVOJI/AAAAAAAARiY/S-BuCAFAxoMssyId1jiDMQp0fRbzsfR3ACLcBGAsYHQ/s320/Pisolitic%2B%25281%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Pisolitic bauxite Photo: James St. John</td></tr>
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Pisolitic</span></b><br />
A mineral of pisolitic habit develops round, pea-shaped forms. These are larger and slightly more uneven than an oolite and are usually composed of calcium carbonate. The word 'pisolitic' is derived from the Greek term pisos, 'pea.'<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-y4LmuglQGBI/XaXfgB7vJLI/AAAAAAAARhA/m5fjtmKVtgYI9rVShBCFLFmrefO1NpQpACLcBGAsYHQ/s1600/Stalactitic%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="700" data-original-width="525" height="320" src="https://1.bp.blogspot.com/-y4LmuglQGBI/XaXfgB7vJLI/AAAAAAAARhA/m5fjtmKVtgYI9rVShBCFLFmrefO1NpQpACLcBGAsYHQ/s320/Stalactitic%2B%25281%2529.jpg" width="240" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Stalactitic Malachite. Photo: Crystal Classics </td></tr>
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Stalactitic</span></b><br />
<div class="separator" style="clear: both; text-align: center;"></div>Stalactitic or columnar crystal habit refers to the tall, tapered, columlike appearance of an icicle or a limestone stalactite. Such formations are built up by the dripping of mineral-laden solution. The minerals calcite and aragonite (CaCO<sub>3</sub>) typically form stalactites. The term is derived from the Greek word stalaktos, 'dripping.'<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-_OdzNDT3zcw/XaXgBO167yI/AAAAAAAARhI/ExrfjCzFkTcgBY4_eL-Omv9Mtg-OHDE7QCLcBGAsYHQ/s1600/Pyrite%2BConcretions%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="600" height="320" src="https://1.bp.blogspot.com/-_OdzNDT3zcw/XaXgBO167yI/AAAAAAAARhI/ExrfjCzFkTcgBY4_eL-Omv9Mtg-OHDE7QCLcBGAsYHQ/s320/Pyrite%2BConcretions%2B%25281%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Pyrite Concretions</td></tr>
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Concretionary</span></b><br />
A concretion develops when mineral matter is concentrically deposited around a nucleus and colored and banded layers are build up. Malachite often exhibits such formations.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-pBlotol1E0o/XaX0041faxI/AAAAAAAARjQ/6WJ6yvQISOU7oCYjJ31rlkeJX-5p0rODgCLcBGAsYHQ/s1600/Striated%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="432" data-original-width="432" height="320" src="https://1.bp.blogspot.com/-pBlotol1E0o/XaX0041faxI/AAAAAAAARjQ/6WJ6yvQISOU7oCYjJ31rlkeJX-5p0rODgCLcBGAsYHQ/s320/Striated%2B%25281%2529.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Striated pyrite </td></tr>
</tbody></table><b><span style="font-family: "georgia" , "times new roman" , serif;">Striated</span></b><br />
Minerals whose crystals are of striated habit display shallow parallel grooves or lines along flat crystal faces. Pyrite often demonstrates square, striated crystals.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-RvQD23uLE2k/XaXdme3uHYI/AAAAAAAARgk/SZRwxRd3lHY-SBGVyd35KNE1au03qqSPQCLcBGAsYHQ/s1600/Drusy%2B%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="Drusy quartz " border="0" data-original-height="616" data-original-width="605" height="320" src="https://1.bp.blogspot.com/-RvQD23uLE2k/XaXdme3uHYI/AAAAAAAARgk/SZRwxRd3lHY-SBGVyd35KNE1au03qqSPQCLcBGAsYHQ/s320/Drusy%2B%25281%2529.jpg" title="" width="314" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Drusy quartz </td></tr>
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<b><span style="font-family: "georgia" , "times new roman" , serif;">Drusy</span></b><br />
A sample exhibiting drusy habit displays a surface covered with a fine furry layer of tiny crystals.<br />
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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-c1MkE14Q2No/XaXrET-Z0NI/AAAAAAAARik/7W7nMrjroKYHKX82W8vuol7ExUSbBzCLQCLcBGAsYHQ/s1600/Massive.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="300" data-original-width="462" height="207" src="https://1.bp.blogspot.com/-c1MkE14Q2No/XaXrET-Z0NI/AAAAAAAARik/7W7nMrjroKYHKX82W8vuol7ExUSbBzCLQCLcBGAsYHQ/s320/Massive.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Massive Amazonite. Photo: Lehighminerals</td></tr>
</tbody></table><br />
<b><span style="font-family: "georgia" , "times new roman" , serif;">Massive</span></b><br />
Massive or earthy habit describes a large, lumpy mass which has no apparent crystal form. In such a sample the crystals are too tiny to be observable by the eye and are interlocked and mingled; the specimen lacks visible crystals. <br />
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<br />
<b><span style="font-family: "georgia" , "times new roman" , serif;">See also:</span></b><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2018/03/crystal-formations-and-their-meanings.html" target="_blank">Crystal Formations and Their Meanings</a></span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2017/01/types-of-mineral-inclusions-with-photos.html" target="_blank">Types of Mineral Inclusions with Photos</a></span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2015/01/killer-minerals-worlds-10-most-deadly.html" target="_blank">The World's 10 Most Deadly Minerals</a></span><br />
<span style="font-family: "georgia" , "times new roman" , serif;"><a href="https://www.geologyin.com/2015/02/top-radioactive-minerals-occurrence.html" target="_blank">Top Radioactive Minerals: Occurrence and Identification</a></span></div>

Crystal Habits and Forms

The term crystal habit describes the favored growth pattern of the crystals of a mineral species, whether individually or in aggregate. It...

Study Confirmed Earth Had Living Organisms 3.5 Billion Years Ago

Earth History, Fossils 8:01 PM

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<tr><td style="text-align: center;"><a href="https://1.bp.blogspot.com/-zQEuFJGInMA/XaIGC7XHCFI/AAAAAAAARfk/lJu5sM950uYeQb9AfJSB6TL75Its7Zn4ACLcBGAsYHQ/s1600/fossilised-microbes-from-3-5-billion-years-ago-are-oldest-yet-found%2B%25282%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="667" data-original-width="1024" height="416" src="https://1.bp.blogspot.com/-zQEuFJGInMA/XaIGC7XHCFI/AAAAAAAARfk/lJu5sM950uYeQb9AfJSB6TL75Its7Zn4ACLcBGAsYHQ/s640/fossilised-microbes-from-3-5-billion-years-ago-are-oldest-yet-found%2B%25282%2529.jpg" width="640" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">It is unclear whether stromatolite rock structures like this one in Western Australia are always produced by living organisms<br />
Auscape/Universal Images Group via Getty Images</td></tr>
</tbody></table>
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<div style="text-align: left;">
<span style="font-family: Georgia, "Times New Roman", serif;">Scientists have found the organic remains of tiny organisms in Western Australia dated at 3.5 billion years old - from near the dawn of life on Earth.</span><br /><br />
The UNSW researchers found the organic matter in stromatolites -- fossilised microbial structures -- from the ancient Dresser Formation in the Pilbara region of Western Australia.<br />
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The stromatolites have been thought to be of biogenic origin ever since they were discovered in the 1980s. However, despite strong textural evidence, that theory was unproven for nearly four decades, because scientists hadn't been able to show the definitive presence of preserved organic matter remains -- until today's publication in journal Geology.<br />
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"This is an exciting discovery -- for the first time, we're able to show the world that these stromatolites are definitive evidence for the earliest life on Earth," says lead researcher Dr Raphael Baumgartner, a research associate of the Australian Centre for Astrobiology in Professor Martin Van Kranendonk's team at UNSW.<br />
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Professor Van Kranendonk says the discovery is the closest the team have come to a "smoking gun" to prove the existence of such ancient life.<br />
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"This represents a major advance in our knowledge of these rocks, in the science of early life investigations generally, and -- more specifically -- in the search for life on Mars. We now have a new target and new methodology to search for ancient life traces," Professor Van Kranendonk says.</div>
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">Drilling deep, looking closely</span></h4>
<div style="text-align: left;">
Ever since the Dresser Formation was discovered in the 1980, scientists have wondered whether the structures were truly microbial and therefore the earliest signs of life.<br />
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"Unfortunately, there is a climate of mistrust of textural biosignatures in the research community. Hence, the origin of the stromatolites in the Dresser Formation has been a hotly debated topic," Dr Baumgartner says.<br />
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"In this study, I spent a lot of time in the lab, using micro-analytical techniques to look very closely at the rock samples, to prove our theory once and for all."<br />
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Stromatolites in the Dresser Formation are usually sourced from the rock surface, and are therefore highly weathered. For this study, the scientists worked with samples that were taken from further down into the rock, below the weathering profile, where the stromatolites are exceptionally well preserved.<br />
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"Looking at drill core samples allowed us to look at a perfect snapshot of ancient microbial life," Dr Baumgartner says.<br />
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Using a variety of cutting-edge micro-analytical tools and techniques -- including high-powered electron microscopy, spectroscopy and isotope analysis -- Dr Baumgartner analysed the rocks.<br />
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He found that the stromatolites are essentially composed of pyrite -- a mineral also known as 'fool's gold' -- that contains organic matter.<br />
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"The organic matter that we found preserved within pyrite of the stromatolites is exciting -- we're looking at exceptionally preserved coherent filaments and strands that are typically remains of microbial biofilms," Dr Baumgartner says.<br />
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The researchers say that such remains have never been observed before in the Dresser Formation, and that actually seeing the evidence down the microscope was incredibly exciting.<br />
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"I was pretty surprised -- we never expected to find this level of evidence before I started this project. I remember the night at the electron microscope where I finally figured out that I was looking at biofilm remains. I think it was around 11pm when I had this 'eureka' moment, and I stayed until three or four o'clock in the morning, just imaging and imaging because I was so excited. I totally lost track of time," Dr Baumgartner says.</div>
<h4 style="text-align: left;">
<span style="font-family: "georgia" , "times new roman" , serif;">Clues for search for life on Mars</span></h4>
<div style="text-align: left;">
Just over two years ago, Dr Baumgartner's colleague Tara Djokic, a UNSW PhD candidate, found stromatolites in hot spring deposits in the same region in WA, pushing back the earliest known existence of microbial life on land by 580 million years.<br />
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"Tara's main findings were these exceptional geyserite deposits that indicate that there have been geysers in this area, and therefore fluid expulsions on exposed land surface," Dr Baumgartner says.<br />
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"Her study was focused on the broader geological setting of the paleo-environment -- lending support to the theory that life originated on land, rather than in the ocean -- whereas my study really went deeper on the finer details of the stromatolite structures from the area."<br />
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The scientists say that both studies are helping us answer a central question: where did humanity come from?<br />
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"Understanding where life could have emerged is really important in order to understand our ancestry. And from there, it could help us understand where else life could have occurred -- for example, where it was kick-started on other planets," Dr Baumgartner says.<br />
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Just last month, NASA and European Space Agency (ESA) scientists spent as week in the Pilbara with Martin Van Kranendonk for specialist training in identifying signs of life in these same ancient rocks. It was the first time that Van Kranendonk shared the region's insights with a dedicated team of Mars specialists -- a group including the Heads of NASA and ESA Mars 2020 missions.<br />
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"It is deeply satisfying that Australia's ancient rocks and our scientific know-how is making such a significant contribution to our search for extra-terrestrial life and unlocking the secrets of Mars," says Professor Van Kranendonk.</div>
<br />
<i><u><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://newsroom.unsw.edu.au/news/science-tech/earliest-signs-life-scientists-find-microbial-remains-ancient-rocks" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://www.unsw.edu.au/" rel="nofollow" target="_blank">University of New South Wales</a>.</span></u></i></div>

Study Confirmed Earth Had Living Organisms 3.5 Billion Years Ago

It is unclear whether stromatolite rock structures like this one in Western Australia are always produced by living organisms Auscape/Un...

Miners Find Diamond Trapped Inside Another Diamond

Diamonds, famous, Geochemistry 7:24 PM

Miners Find Diamond Trapped Inside Another Diamond

Inside this small diamond is a freely moving second diamond.(Image: © Alrosa) The first of its kind yet known, the unusual gem from a ...

Scientists Discover 30-Million-Year-Old Tiny 'Mold Pigs'

amber, Fossils 7:07 PM

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<span style="font-family: "georgia" , "times new roman" , serif;">Researcher Discovers 'Mold Pig' That is Deemed a New Species of an Invertebrate That Grew Up to 100 Micrometers, Feasted on Fungi and Lived 30 Million Years Ago</span><br />
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Fossils preserved in Dominican amber reveal a new family, genus and species of microinvertebrate from the mid-Tertiary period, a discovery that shows unique lineages of the tiny creatures were living 30 million years ago.<br />
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The findings by George Poinar Jr. of the Oregon State University College of Science give a rare look at a heretofore unknown clade of invertebrates, along with their fungal food source and other animals that lived in their habitat.<br />
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Poinar, an international expert in using plant and animal life forms preserved in amber to learn more about the biology and ecology of the distant past, informally calls the new animals "mold pigs" for their resemblance to swine, and their diet. Scientifically, they are Sialomorpha dominicana, from the Greek words for fat hog (sialos) and shape (morphe).<br />
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Invertebrate means not having a backbone, and invertebrates account for roughly 95 percent of animal species.<br />
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"Every now and then we'll find small, fragile, previously unknown fossil invertebrates in specialized habitats," Poinar said. "And occasionally, as in the present case, a fragment of the original habitat from millions of years ago is preserved too. The mold pigs can't be placed in any group of currently existing invertebrates -- they share characteristics with both tardigrades, sometimes referred to as water bears or moss pigs, and mites but clearly belong to neither group."<br />
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The several hundred individual fossils preserved in the amber shared warm, moist surroundings with pseudoscorpions, nematodes, fungi and protozoa, Poinar said.<br />
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"The large number of fossils provided additional evidence of their biology, including reproductive behavior, developmental stages and food," he said. "There is no extant group that these fossils fit into, and we have no knowledge of any of their descendants living today. This discovery shows that unique lineages were surviving in the mid-Tertiary."<br />
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The Tertiary period began 65 million years ago and lasted for more than 63 million years.<br />
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About 100 micrometers long, the mold pigs had flexible heads and four pairs of legs. They grew by molting their exoskeleton and fed mainly on fungi, supplementing that food source with small invertebrates.<br />
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"No claws are present at the end of their legs as they are with tardigrades and mites," Poinar said. "Based on what we know about extant and extinct microinvertebrates, S. dominicana appears to represent a new phylum. The structure and developmental patterns of these fossils illustrate a time period when certain traits appeared among these types of animals. But we don't know when the Sialomorpha lineage originated, how long it lasted, or whether there are descendants living today."<br />
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<br />
<u><i><span style="font-family: "trebuchet ms" , sans-serif;">The above story is based on <a href="https://today.oregonstate.edu/news/meet-%E2%80%98mold-pigs%E2%80%99-new-group-invertebrates-30-million-years-ago" rel="nofollow" target="_blank">Materials</a> provided by <a href="http://oregonstate.edu/" rel="nofollow" target="_blank">Oregon State University</a>. Original written by Steve Lundeberg.</span></i></u></div>

Scientists Discover 30-Million-Year-Old Tiny 'Mold Pigs'

Researcher Discovers 'Mold Pig' That is Deemed a New Species of an Invertebrate That Grew Up to 100 Micrometers, Feasted on Fun...

What Causes Color in Topaz?

gemstones, Mineral, Mineralogy 8:14 PM

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Topaz is a silicate mineral of aluminium and fluorine with the chemical formula Al<sub>2</sub>SiO<sub>4</sub>(F, OH)<sub>2</sub>. Topaz crystallizes in the orthorhombic system, and its crystals are mostly prismatic terminated by pyramidal and other faces.<br />
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Topaz is usually colorless in the absence of impurities. It is one of the hardest naturally occurring minerals (Mohs hardness of 8) and is the hardest of any silicate mineral.<br />
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The common impurity found in topaz is iron, but iron does not impart any color directly to topaz as chromium impurities do in rubies, which impart the red color. In rubies the chromium atoms are excited directly by absorbing visible photons of light.<br />
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The chromium atoms that jump to an excited state emit light in the red region of the visible spectrum when they return to their ground states. In the case of topaz the iron atoms create another unstable species in the crystal, and this new species jumps to an excited state by absorbing a visible photon of light, which emits light from different regions of the spectrum depending on their wave length, when they return to the ground state, giving rise to the variety of colors found in topaz, including the golden yellow or golden brown color of the “American Golden Topaz.” The unstable species created by the iron atoms are known as “Color Centers.”<br />
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Naturally colored topaz such as yellow, orange and brown topaz contain color centers that are stable to light. If a colorless topaz is irradiated by ultraviolet light, x-rays, gamma rays or high energy electrons, we can obtain a yellow, orange or brown color, but this color is usually unstable and fades in a few days in light.<br />
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However blue topaz produced by irradiation produces color centers which are stable like the color centers of natural blue topaz, and therefore does not fade in light. These color centers can only be destroyed by heating, when the topaz becomes colorless again.<br />
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<b><span style="font-family: Georgia, "Times New Roman", serif;">See also:</span></b><br />
<span style="font-family: Georgia, "Times New Roman", serif;"><a href="https://www.geologyin.com/2019/01/a-gemstone-that-looks-like.html" target="_blank"><span data-offset-key="6t2em-0-0"><span data-text="true">A Gemstone That Looks Like Deconstructed Chocolate Bars</span></span></a></span><br />
<span style="font-family: Georgia, "Times New Roman", serif;"><a href="https://www.geologyin.com/2019/05/moonstone-vs-opal-whats-difference.html" target="_blank"><span data-offset-key="6t2em-0-0"><span data-text="true"><span data-offset-key="4lnbr-0-0"><span data-text="true">Moonstone Vs Opal — What's the Difference?</span></span> </span></span></a></span> <br />
<span style="font-family: Georgia, "Times New Roman", serif;"><a href="https://www.geologyin.com/2019/06/what-is-fire-agate.html" target="_blank">What is Fire Agate?</a></span><br />
<br /></div>

What Causes Color in Topaz?

Topaz is a silicate mineral of aluminium and fluorine with the chemical formula Al 2 SiO 4 (F, OH) 2 . Topaz crystallizes in the ortho...

The New Largest Blue Diamond Found

Diamonds, Mining 6:46 PM

The New Largest Blue Diamond Found

This is the 20.08 carat blue gem quality Type IIb diamond recovered at Cullinan mine. A blue diamond could fetch $15 million Petr...