Mineraloid

A mineraloid is a naturally occurring 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 is considered a mineraloid because the included calcite and/or aragonite crystals are bonded by an organic material, and there is no definite proportion of the components.

Examples

• Allophane solid (IMA/CNMNC valid mineral name)
• Anthracite or hard coal
• Amber, non-crystalline structure, organic
• Bituminous coal
• Chlorophaeite[1]
• Chrysocolla solid (IMA/CNMNC valid mineral name)
• Deweylite, a mixture of serpentine and talc or stevensite[2]
• Diatomite
• Jet, non-crystalline nature, organic (very compact coal)
• Lapis lazuli
• Lechatelierite, nearly pure silica glass, solid (IMA/CNMNC valid mineral name)
• Leonardite
• Lignite, or brown coal
• Libyan desert glass
• Limonite, a mixture of oxides and hydroxides of iron
• Mercury, liquid (IMA/CNMNC valid mineral name)
• Moldavite
• Obsidian, volcanic glass – non-crystalline structure, a silica rich glass
• Opal, non-crystalline hydrated silica silicon dioxide, solid (IMA/CNMNC valid mineral name)
• Ozokerite, a black waxy hydrocarbon mixture
• Palagonite[1]
• Pearl, organically produced carbonate
• Pele's hair
• Petroleum, liquid, organic
• Psilomelane
• Pumice
• Pyrobitumen, amorphous fossilized petroleum (noncrystalline, organic)
• Sideromelane,[1] volcanic glass – non-crystalline, an iron rich, silica poor glass
• Shungite, black, lustrous, more than 98 weight percent of carbon
• Tektite, meteoritic silica rich glass
• Water, e. g. as inclusions in other crystals, liquid
• Zietrisikite, a mineral hydrocarbon wax

See also

• List of minerals – Mineraloids are listed after minerals in each alphabetically sorted section.

References

1. Peacock, M. A.; Fuller, R. E. (1928). "Chlorophaeite, sideromelane, and palagonite from the Columbia River Plateau" (PDF). American Mineralogist. 13: 360–382. Retrieved 6 September 2017.
2. Schandl, Eva S.; Gorton, Michael P. (1995). "Phyllosilicate Alteration of Olivine in The Lower Sheeted Dike Complex, Leg 140, Hole 504B" (PDF). Proceedings of the Ocean Drilling Program, Scientific Results. 137/140: 207–216. doi:10.2973/odp.proc.sr.137140.019.1995. ISSN 1096-7451.

External links

• The Mineraloids Class. Amethyst Galleries.