Editing Mineraloid

{{short description|Non-crystalline mineral-like substance}}{{More citations needed|date=April 2024}}

A '''mineraloid''' is a naturally occurring substance that resembles a [[mineral]], but does not demonstrate the [[crystallinity]] of a mineral. Mineraloid substances possess [[chemical composition]]s that vary beyond the generally accepted ranges for specific minerals, for example, [[obsidian]] is an [[amorphous]] [[glass]] and not a true [[crystal]]; lignite ([[jet (lignite)|jet]]) is derived from the decay of wood under extreme pressure underground; and [[opal]] is a mineraloid substance because of its non-crystalline nature. [[Pearl]] is a mineraloid substance because the [[calcite]] crystals and the [[aragonite]] crystals are bonded by an organic material, and naturally occurs without definite proportions of the components.

The first usage of the term ''mineraloid'' substance was in 1909, by mineralogist and geologist Julian Niedzwiedzki, in identifying and describing amorphous substances that resemble minerals.<ref>{{Cite journal |last=Titamgim |first=Dirk |date=1988 |title=Rock Chips: What is a Mineraloid? |journal=Rocks & Minerals |volume=63 |issue=1 |pages=65 |doi=10.1080/00357529.1988.11761818}}</ref>

==Examples==
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* [[Allophane]], solid (IMA/CNMNC valid mineral name)
* [[Amber]], non-crystalline structure, organic
* [[Anthracite]] or hard coal
* [[Bituminous coal]]
* [[Chlorophaeite]]<ref name="peacock">{{cite journal|last1=Peacock|first1=M. A.|last2=Fuller|first2=R. E.|date=1928|title=Chlorophaeite, sideromelane, and palagonite from the Columbia River Plateau|url=http://rruff.info/doclib/am/vol13/AM13_360.pdf|journal=[[American Mineralogist]]|volume=13|pages=360&ndash;382|access-date=6 September 2017}}</ref>
* [[Chrysocolla]], solid (IMA/CNMNC valid mineral name)
* [[Deweylite]], a mixture of [[Serpentine subgroup|serpentine]] and [[talc]] or [[stevensite]]<ref name="Schandl1995">{{cite journal|last1=Schandl|first1=Eva S.|last2=Gorton|first2=Michael P.|year=1995|title=Phyllosilicate Alteration of Olivine in The Lower Sheeted Dike Complex, Leg 140, Hole 504B|url=http://www-odp.tamu.edu/publications/137_140_SR/VOLUME/CHAPTERS/137_140_18.pdf|journal=Proceedings of the Ocean Drilling Program, Scientific Results|series=Proceedings of the Ocean Drilling Program|volume=137/140|pages=207–216|doi=10.2973/odp.proc.sr.137140.019.1995|issn=1096-7451|doi-access=free}}</ref>
* [[Diatomite]]
* [[Ebonite]],{{citation needed|date=May 2021}} vulcanized natural or synthetic rubber (organic); lacks a crystalline structure
* [[Fulgurite]], a variety of the mineraloid lechatelierite
* [[Jet (lignite)|Jet]], non-crystalline nature, organic (very compact coal)
* [[Lechatelierite]], nearly pure silica glass, solid (IMA/CNMNC valid mineral name)
* [[Leonardite]]
* [[Libyan desert glass]]
* [[Lignite]]—brown coal 
* [[Limonite]], a mixture of oxides and hydroxides of iron
* [[Mercury (element)|Mercury]], (as liquid)
* [[Moldavite]]
* [[Radiolarite|Mookaite/Radiolarite]]
* [[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]]<ref name=peacock/> 
* [[Pearl]], organically produced carbonate
* [[Pele's hair]]
* [[Petroleum]], liquid, organic 
* [[Psilomelane]]
* [[Pumice]]
* [[Pyrobitumen]], amorphous fossilized petroleum (noncrystalline, organic)
* [[Shungite]], black, lustrous, more than 98 [[Mass fraction (chemistry)|weight percent]] of carbon
* [[Sideromelane]],<ref name=peacock/> volcanic glass – non-crystalline, an iron rich, silica poor glass 
* [[Tektite]], meteoritic silica rich glass
* [[Water]], e.g. as inclusions in other crystals, or in the form of [[rain]], (as liquid)
* [[Zietrisikite]], a mineral hydrocarbon wax
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==See also==
*[[List of minerals]] – Mineraloids are listed after minerals in each alphabetically sorted section.

==References==
{{Reflist}}

==External links==
* [http://www.galleries.com/minerals/mineralo/class.htm The Mineraloids Class]. Amethyst Galleries.

[[Category:Mineralogy]]

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