Chemicals/Mineraloids

A mineraloid is a substance that does not show or have crystallinity.

This Lechatelierite was created by high voltage power line arcing on rocky soil. Credit: Kessmess.

The image on the right is of lechatelierite which was created by a high voltage power line arcing to rocky soil.

Theoretical mineraloidsEdit

Def. a "substance that resembles a mineral but does not exhibit crystallinity"[1] is called a mineraloid.

EbonitesEdit

 
These ebonite applications are from the 19th century. Credit: FBQ.

Def. a "hard rubber especially when black or unfilled"[2] is called an ebonite.

LimonitesEdit

 
Limonite is an amorphous mineraloid of a range of hydrated iron oxides. Credit: USGS.

Limonite is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO(OH)·nH2O, although this is not entirely accurate as the ratio of oxide to hydroxide can vary quite widely. Limonite is one of the two principle iron ores, the other being hematite, and has been mined for the production of iron since at least 2500 BCE.[3][4] Although originally defined as a single mineral, limonite is now recognized as a mixture of related hydrated iron oxide minerals, among them goethite, akaganeite, lepidocrocite, and jarosite. Individual minerals in limonite may form crystals, but limonite does not, although specimens may show a fibrous or microcrystalline structure,[5] and limonite often occurs in concretionary forms or in compact and earthy masses; sometimes mammillary, botryoidal, reniform or stalactitic. Because of its amorphous nature, and occurrence in hydrated areas limonite often presents as a clay or mudstone. However there are limonite pseudomorphs after other minerals such as pyrite.[6] This means that chemical weathering transforms the crystals of pyrite into limonite by hydrating the molecules, but the external shape of the pyrite crystal remains. Limonite pseudomorphs have also been formed from other iron oxides, hematite and magnetite; from the carbonate siderite and from iron rich silicates such as almandine garnets. Limonite usually forms from the hydration of hematite and magnetite, from the oxidation and hydration of iron rich sulfide minerals, and chemical weathering of other iron rich minerals such as olivine, pyroxene, amphibole, and biotite. It is often the major iron component in lateritic soils. One of the first uses was as a pigment. The yellow form produced yellow ochre for which Cyprus was famous.[7]

PetroleumsEdit

 
This is a natural oil (petroleum) seep near Korňa, Kysucké Beskydy, Western Carpathians, Slovakia. Credit: Branork.

Def. a "flammable liquid ranging in color from clear to very dark brown and black, consisting mainly of hydrocarbons, occurring naturally in deposits under the Earth's surface"[8] is called a petroleum.

Coal tarsEdit

 
The lake tar pit at the La Brea Tar Pits is in Los Angeles, CA, USA. Credit: Buchanan-Hermit.

Def. a "black, oily, sticky, viscous substance, consisting mainly of hydrocarbons produced by the distillation of [derived from][9] organic materials such as wood, peat, or coal"[10] is called a tar.

Def. a "black, viscous tar made by the destructive distillation of coal (to make coke and town gas)"[11] is called a coal tar.

It contains at least benzene, naphthalene, phenols, and aniline.

NaphthasEdit

 
The beaker contains open-specification naphtha from Bangladesh. Credit: Gurumia.com.

Def. "any of a wide variety of aliphatic or aromatic liquid hydrocarbon mixtures distilled from petroleum or coal tar"[12] is called a naphtha.

MalthasEdit

Def. a black viscid substance intermediate between petroleum and asphalt is called a maltha, or malthite.

BitumensEdit

 
Here, Lussatite, an opal, occurs with bitumen. Credit: Parent Géry.

Def. a black viscous mixture of hydrocarbons obtained naturally is called a bitumen.

In the image on the right, bitumen occurs with lussatite, an opal.

PitchsEdit

 
Pitch Lake (Asphalt Lake) near La Brea on the island of Trinidad in the West Indies is the largest natural Tar or Bitumen Lake in the world. Credit: Richard Seaman.
 
Mother-of-the-Lake, Pitch Lake, is in Trinidad. Credit: Jw2c.

Def. a "dark, extremely viscous material [remaining in still after distilling crude oil and][13] made by distilling tar"[14] is called a pitch.

AsphaltsEdit

 
Hand sample including natural asphalt, from Slovakia. Credit: Piotr Gut.

Def. a "sticky, black and highly viscous liquid or semi-solid, composed almost entirely of bitumen, that is present in most crude petroleums and in some natural deposits"[15] is called an asphalt.

ZietrisikitesEdit

Def. a natural, waxy hydrocarbon mineral is called a zietrisikite.

OzoceritesEdit

 
Ozokerite is from the Bringham Young University Department of Geology, Provo, Utah, collection. Credit: Andrew Silver, USGS.

Def. a natural dark, or black, odoriferous mineral wax is called ozokerite, or ozocerite.

AmbersEdit

 
These are naturally occurring amber stones. Credit: Lanzi.
 
This is natural blue dominican amber. Credit: Vassil.
 
Pendants made from amber. Credit: Adrian Pingstone.{{free media}}

Def. a "hard, [generally][16] yellow to brown translucent fossil resin"[17] is called amber.

ObsidiansEdit

 
This is a specimen of obsidian from Lake County, Oregon. Credit: Locutus Borg.

An example of obsidian is shown on the right. Obsidian is a naturally occurring glass. Glass is an extremely viscous liquid.

Def. a naturally occurring black glass is called an obsidian.

SideromelanesEdit

 
This sideromelane is from Hawaii. Credit: James St. John.{{free media}}
 
Rich golden brown-colored basaltic glass is called sideromelane. Credit: James St. John.{{free media}}

Sideromelane is a vitreous basaltic volcanic glass, usually occurring in palagonite tuff, for which it is characteristic.

Reticulite from Kilauea volcano in Hawaii, USA, is solidified lava that was erupted by a lava fountain at Kilauea's East Rift Zone. Reticulite is also known as thread-lace scoria. It is greenish-brown, highly vesiculated basaltic glass (sideromelane) and it has a complex three-dimensional honeycomb structure. This sample is 18 millimetres across.


Mt. Kilauea is the world’s most active volcano. It sits atop the Hawaii Hotspot in the central Pacific Ocean. It had a decades-long eruption from 1983 to 2018. Kilauea lavas are basaltic in composition, but the physical appearance of Kilauea’s output varies tremendously. Many of Kilauea’s ongoing basaltic eruptions have occurred along its East Rift Zone, a fracture system extending ~eastward from the summit vent area.

The rock shown here is from the thin ceiling of a lava tube that was active during the 1969 to 1974 eruption of the Mauna Ulu Vent. The Mauna Ulu Lava Field is located along Kilauea’s East Rift Zone. This lava tube ceiling specimen ranges from 1 to 3.5 cm thick.

The photo depicts the exterior (upper) surface of a lava tube ceiling. Abundant, consolidated basalt glass filaments are present, formed by stretching. In cross-section view, the rock is seen to be a highly vesiculated basaltic glass. Rich golden brown-colored basaltic glass is called sideromelane.

TektitesEdit

 
Two splash-form tektites here are molten terrestrial ejecta from a meteorite impact. Credit: Brocken Inaglory.{{free media}}

Def. a "small, round, dark glassy object, composed of silicates, formed by the rapid cooling of meteorite fragments that hit the Earth"[18] is called a tektite.

OpalsEdit

 
These are blue opals from Succor Creek, Oregon, USA. Credit: Rica Rika.
 
This is an idealized diagram of the apparent structure of opal. Credit: Dpulitzer.
 
Massive dark blue and fluorescent banded opal from Barco River, Queensland, Australia. Credit: Aramgutang.{{free media}}

Def. a naturally occurring, hydrous, amorphous form of silica, where 3% to 21% of the total weight is water is called an opal.

On the right are light blue opals from Succor Creek, Oregon, USA. On the left is an idealized diagram of the structure of opal consisting of spheres of silica arranged in an orderly manner.

On the lower left, by contrast to the light blue opals on the right, is massive dark blue and fluorescent banded opal.

LechatelieritesEdit

Lechatelierite is amorphous SiO2, or silica glass.

PearlsEdit

 
Various natural pearls are shown. Credit: MASAYUKI KATO.

Def. a "shelly concretion, usually rounded, and having a brilliant luster, with varying tints, found in the mantle, or between the mantle and shell, of certain bivalve mollusks, [...] and sometimes in certain univalves"[19] is called a pearl.

QuasicrystalsEdit

 
Ho-Mg-Zn dodecahedral quasicrystal, grown by using the self-flux method (excess Mg), and slowly cooling from 700 C to 480 C. Credit: Ames Laboratory, US Department of Energy.

A crystalline substance that falls into a periodic pattern, or space group, in three dimensions, can be a mineral, or crystalline solid.

A quasicrystal consists of an ordered array of atoms or molecules without periodicity. They display a discrete pattern in X-ray diffraction but do not fall into any space group.

HypothesesEdit

  1. A mineral is a naturally occurring or naturally produced crystalline substance displaying space-filling periodicity.

See alsoEdit

ReferencesEdit

  1. Equinox (24 October 2008). "mineraloid". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 2012-10-23. {{cite web}}: |author= has generic name (help)
  2. Philip B. Gove, ed (1963). Webster's Seventh New Collegiate Dictionary. Springfield, Massachusetts: G. & C. Merriam Company. pp. 1221. 
  3. MacEachern, Scott (1996) "Iron Age beginnings north of the Mandara Mountains, Cameroon and Nigeria" pp. 489–496 In Pwiti, Gilbert and Soper, Robert (editors) (1996) Aspects of African Archaeology: Proceedings of the Tenth Pan-African Congress University of Zimbabwe Press, Harare, Zimbabwe, ISBN 978-0-908307-55-5; archived here by Internet Archive on 11 March 2012
  4. Diop-Maes, Louise Marie (1996) "La question de l'Âge du fer en Afrique" ("The question of the Iron Age in Africa") Ankh 4/5: pp. 278–303, in French; archived here by Internet Archive on 25 January 2008
  5. Boswell, P. F. and Blanchard, Roland (1929) "Cellular structure in limonite" Economic Geology 24(8): pp. 791–796
  6. Northrop, Stuart A. (1959) "Limonite" Minerals of New Mexico (revised edition) University of New Mexico Press, Albuquerque, New Mexico, pp. 329–333 }}
  7. Constantinou, G. and Govett, G. J. S. (1972) "Genesis of sulphide deposits, ochre and umber of Cyprus" Transactions of the Institution of Mining and Metallurgy 81: pp. 34–46
  8. Stalker~enwiktionary (13 November 2003). "petroleum". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 2015-01-09. {{cite web}}: |author= has generic name (help)
  9. Dmh (6 November 2004). "tar". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 2021-04-30. {{cite web}}: |author= has generic name (help)
  10. Mud~enwiktionary (29 May 2004). "tar". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 2015-01-09. {{cite web}}: |author= has generic name (help)
  11. SemperBlotto (22 June 2005). "coal tar". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 22 June 2021. {{cite web}}: |author= has generic name (help)
  12. SemperBlotto (27 April 2006). "naphtha". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 2015-01-09. {{cite web}}: |author= has generic name (help)
  13. Gregorydavid (24 August 2006). pitch. San Francisco, California: Wikimedia Foundation, Inc. https://en.wiktionary.org/wiki/pitch. Retrieved 2015-01-10. 
  14. Ortonmc (20 December 2003). pitch. San Francisco, California: Wikimedia Foundation, Inc. https://en.wiktionary.org/wiki/pitch. Retrieved 2015-01-10. 
  15. JillianE (14 February 2006). asphalt. San Francisco, California: Wikimedia Foundation, Inc. https://en.wiktionary.org/wiki/asphalt. Retrieved 2015-01-09. 
  16. -sche (28 August 2011). "amber". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 2015-01-09. {{cite web}}: |author= has generic name (help)
  17. Bluelion~enwiktionary (8 May 2003). "amber". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 2015-01-09. {{cite web}}: |author= has generic name (help)
  18. SemperBlotto (6 November 2006). "tektite". San Francisco, California: Wikimedia Foundation, Inc. Retrieved 2012-10-23. {{cite web}}: |author= has generic name (help)
  19. Poccil (20 October 2004). pearl. San Francisco, California: Wikimedia Foundation, Inc. https://en.wiktionary.org/wiki/pearl. Retrieved 2015-07-19. 

External linksEdit

{{Chemistry resources}}