A mineraloid is a naturally occurring substance that resembles a
mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...
, but does not demonstrate the
crystallinity of a mineral. Mineraloid substances possess
chemical compositions that vary beyond the generally accepted ranges for specific minerals, for example,
obsidian is an
amorphous
In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid) is a solid that lacks the long-range order that is a characteristic of a crystal. The terms "glass" and "glassy solid" are sometimes used synonymousl ...
glass
Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window pane ...
and not a true
crystal; lignite (
jet) is derived from the decay of wood under extreme pressure underground; and
opal
Opal is a hydrated amorphous form of silicon dioxide, silica (SiO2·''n''H2O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to the amorphous (chemical) physical structure, it is classified as a ...
is a mineraloid substance because of its non-crystalline nature.
Pearl is a mineraloid substance because the
calcite
Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...
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.
Examples
*
Allophane, solid (IMA/CNMNC valid mineral name)
*
Amber, non-crystalline structure, organic
*
Anthracite or hard coal
*
Bituminous coal
Bituminous coal, or black coal, is a type of coal containing a tar-like substance called bitumen or asphalt. Its coloration can be black or sometimes dark brown; often there are well-defined bands of bright and dull material within the coal seam, ...
*
Chlorophaeite
*
Chrysocolla, solid (IMA/CNMNC valid mineral name)
*
Deweylite, a mixture of
serpentine and
talc or
stevensite
*
Diatomite
*
Ebonite, 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
Opal is a hydrated amorphous form of silicon dioxide, silica (SiO2·''n''H2O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to the amorphous (chemical) physical structure, it is classified as a ...
, non-crystalline hydrated silica silicon dioxide, solid (IMA/CNMNC valid mineral name)
*
Ozokerite, a black waxy hydrocarbon mixture
*
Palagonite[
* Pearl, organically produced carbonate
* Pele's hair
* ]Petroleum
Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring un ...
, liquid, organic
* Psilomelane
* Pumice
* Pyrobitumen, amorphous fossilized petroleum (noncrystalline, organic)
* Shungite, black, lustrous, more than 98 weight percent of carbon
* Sideromelane,[ volcanic glass – non-crystalline, an iron rich, silica poor glass
* Tektite, meteoritic silica rich glass
* ]Water
Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...
, e.g. as inclusions in other crystals, or in the form of rain
Rain is a form of precipitation where water drop (liquid), droplets that have condensation, condensed from Water vapor#In Earth's atmosphere, atmospheric water vapor fall under gravity. Rain is a major component of the water cycle and is res ...
, (as liquid)
* Zietrisikite, a mineral hydrocarbon wax
See also
* List of minerals – Mineraloids are listed after minerals in each alphabetically sorted section.
References
External links
The Mineraloids Class
Amethyst Galleries.
Mineralogy
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