What Is the Difference Between a Mineral and a Mineraloid?
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What Is the Difference Between a Mineral and a Mineraloid? Photo by: Energy Muse |
Mineraloids are most often placed with mineral specimens, or one does not know exactly how to classify them. They come up in conversations among rock-hounds and collecting enthusiasts without the knowledge that they are pseudo-minerals. They are not true minerals because they are missing key components of what defines a mineral, and those key components are in their structure and origin.
A mineral is a naturally occurring chemical compound, usually of crystalline form and abiogenic in origin (not produced by life processes). A mineral has one specific chemical composition, whereas a rock can be an aggregate of different minerals or mineraloids. The study of minerals is called mineralogy. (How to Identify Common Minerals?)
A mineraloid is a mineral-like substance that does not demonstrate crystallinity. Mineraloids possess chemical compositions that vary beyond the generally accepted ranges for specific minerals. For example, obsidian is an amorphous glass and not a crystal. Jet is derived from decaying wood under extreme pressure. Opal is another mineraloid because of its non-crystalline nature. Pearl, considered by some to be a mineral because of the presence of calcium carbonate crystals within its structure, would be better considered a mineraloid because the crystals are bonded by an organic material, and there is no definite proportion of the components.
Famous Mineraloid
- Amber – fossilized tree resin
- Pearl – organically formed containing mostly calcium carbonate
- Mookaite/Radiolarite – Yes! It’s of organic origin (even though it’s seen more readily as a chalcedony)
- Opal – hydrated silica where the water amount within various from stone to stone
- Lechatelierite – silica lightning strike in sand commonly called a fulgurite
- Libyan Desert Glass – also formed from a lightning strike in sand
- Mercury – a liquid metal
- Coal – formed organically from plants
- Jet – a type of rare, hard, black coal and popular mineraloid in jewelry often confused as black onyx
- Obsidian – silica glass made from the rapid cooling of volcanic lava
- Pumice – igneous rock that cools and solidifies so quickly that the atoms are not definitively ordered
- Tektite – silica glass made of obsidian that is earth-origin but was launched into space outside of the atmosphere for a bit and returned
- Moldavite – a type of tektite prized for its green color
- Ebonite – organically formed natural rubber like substance lacking in uniform crystalline structure
- Limonite – hydrated iron oxide mixture – containing water with no definite crystal structure
- Petroleum – an organic liquid
- Pyrobitumen – amorphous fossilized petroleum (noncrystalline, organic)
- Water – Yes! water can be classified as a mineraloid, as it meets the definition of a mineraloid