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Non-crystalline mineral-like substance
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.
The term was first introduced in 1909 by mineralogist and geologist
Julian Niedzwiedzki , in reference to amorphous substances resembling minerals.
[1]
Examples
Allophane , solid (IMA/CNMNC valid mineral name)
Amber , non-crystalline structure, organic
Anthracite or hard coal
Bituminous coal
Chlorophaeite
[2]
Chrysocolla , solid (IMA/CNMNC valid mineral name)
Deweylite , a mixture of
serpentine and
talc or
stevensite
[3]
Diatomite
Ebonite ,[
citation needed ] vulcanized natural or synthetic rubber (organic); lacks a crystalline structure
Fulgurite , a variety of the mineraloid lechatelierite
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 , (as liquid)
Moldavite
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
[2]
Pearl , organically produced carbonate
Pele's hair
Petroleum , liquid, organic
Psilomelane
Pumice
Pyrobitumen , amorphous fossilized petroleum (noncrystalline, organic)
Shungite , black, lustrous, more than 98
weight percent of carbon
Sideromelane ,
[2] 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
See also
List of minerals – Mineraloids are listed after minerals in each alphabetically sorted section.
References
^ Titamgim, Dirk (1988). "Rock Chips: What is a Mineraloid?". Rocks & Minerals . 63 (1): 65.
doi :
10.1080/00357529.1988.11761818 .
^
a
b
c 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 .
^ 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 . Proceedings of the Ocean Drilling Program. 137/140: 207–216.
doi :
10.2973/odp.proc.sr.137140.019.1995 .
ISSN
1096-7451 .
External links