Minerals/Carbonides

Carbonides are naturally occurring minerals composed of 50 atomic percent, or more, carbon. Carbonide-like minerals with greater than 25 at % carbon are also included. This separates carbon containing minerals from carbonates which are at most 25 at % carbon.

This diamond is a nearly perfectly-formed yellow diamond crystal weighing about 253.7 carats (50.74 g). Credit: Eurico Zimbres FGEL/UERJ.

Diamonds

The crystal is a single octohedron with intricately stepped faces. Credit: Robert Lavinsky.

Def. "[a] naturally occurring, glimmering glass-like allotrope of carbon in which each atom is surrounded by four others in the form of a tetrahedron" is called a diamond.

The diamond imaged on the right has been estimated to be just over 1.5 carats. It measures 5 mm on edge. Although it might seem small, it has wonderful visual impact because of the clarity and perch on matrix. Embedded perhaps 50% in the matrix, so you know it is real. What is more, you can look right through the diamond to the matrix underneath! Around the diamond is a thin white layer you sometimes see, which indicates not glue but rather an alteration in the surrounding rock due to the chemical heat of formation of the crystal and is a good indication of its origins as natural.

Graphites

Natural, or native element, piece of graphite has been cut from a larger piece. Credit: USGS.{{free media}}

Graphite is a hexagonal form of carbon that often appears as tabular crystals.

Chaoites

File:Chaoite.jpg

This is a geniune natural piece of chaoite at 21.60 ct. Credit: SnipView. {{fairuse}}

Chaoites are another hexagonal form of native carbon. It occurs as "thin lamellae (3-15 microns wide), alternating with graphite and perpendicular to the {0001} face of graphite."

"Occurs in association with graphite, zircon, and rutile in shocked graphite gneisses from Mottingen in the Ries Crater, Germany. Also observed from the Goalpara and Dyalpur carbonaceous chondrites."

Lonsdaleites

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The mineral Lonsdaleite is made from carbon with a different arrangement than diamond. Credit: payam.{{fairuse}}

"The mineral Lonsdaleite is a translucent, brownish yellow and is made from the atoms of carbon but the arrangement of these atoms is different from the arrangement of carbon atoms in a diamond. [...] The mineral is very rare and is formed naturally whenever [...] graphite containing meteorites fall on the earth and hit the surface."

"Found in the Canyon Diablo and Goalpara meteorites."

Fullerites

Fullerite appears to be a tentative name for the mineral occurrence of buckyballs.

"By means of high-resoluton transmission electron microscopy, both C60 and C70 fullerenes have been found in a, carbon-rich Precambrian rock from Russia The fullerenes were confirmed by Fourier transform mass spectrometry with both laser desorption and thermal desorption/electron-capture methods to verify that the fullerenes were indeed present in the geological sample".

Space carbons

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This is a piece of carbon from space. Credit: Francine Loubrieu.

Apparently graphitic-like carbon particles such as shown in the image on the right have been found in space and brought back to Earth.

Organic minerals

An organic mineral appears to be a naturally occurring mineral containing one or more organic chemicals at a concentration of greater than 25 molecular %.

Carpathites

Radial spray of highly lustrous, canary-yellow carpathite lathes reach to 2.0 cm. Credit: Rob Lavinsky.

This is carpathite under ultraviolet light. Credit: Rama.

Carpathite (aka Karpatite) is a very rare organic species (C₂₄H₁₂). It is a polycyclic aromatic hydrocarbon (PAH). This specimen is from the old Picacho Mercury Mine of California. It exhibits a radial spray of highly lustrous, canary-yellow carpathite lathes to 2.0 cm on drusy quartz. Another crossed cluster of crystals above reach 3.0 cm. It has 66.7 at % carbon.

Idrialites

A very rare, greenish yellow, orthorhombic, organic mineral, curtisite is a synonym for idrialite. Credit: Rob Lavinsky.

With a formula of C₂₂H₁₄, idrialites are about 61 at % carbon.

Idrialite is "a complex natural mineral composed entirely of cata-condensed polyaromatic hydrocarbons (PAHs), usually containing a thiophenic or aliphatic five-membered ring."

Idrialite "(and also curtisite) represents more complex mixtures of chain-type PAHs with molecular weights ranging from 216 to 372 amu [5]."

"Some of the bands in the idrialite spectra are attributed to specific vibrational modes of thiophene or fluorene-type PAHs, especially in the region bellow 1000 cm⁻¹. These modes at 495, 705 and 750 cm⁻¹ along with C–H or C–H₂ stretching modes around 3000 cm⁻¹ can be then used to distinguish such groups of PAHs in complicated organic mineral mixtures like idrialite."

Idrialite may include benzonaphthothiophenes (chemical formula: C₁₆H₁₀S).

Kratochvilites

Def. a "rare organic mineral [C₁₄H₁₀ or (C₆H₄)₂CH₂, a polymorph of fluorene], an orthorhombic hydrocarbon formed by combustion of coal or pyritic black shale deposits" is called kratochvilite

Kratochvilites have about 58.3 at % carbon.

Moissanite

Moissanite is native SiC. Credit: Andrew Silver.

Moissanite is native SiC.

Hoelites

Yellow acicular crystals of Hoelite (picture size: 10 mm) are from Carolaschacht Mine, Freital near Dresden, Saxony, Germany. Credit: Thomas Witzke.

Hoelites are 50 at % carbon with a formula of (C₆H₄)₂(CO)₂.

Abelsonites

The reddish abelsonite crystal is 1.8 mm long. Credit: Thomas Witzke.

Abelsonites have a chemical formula of NiC₃₁H₃₄N₄, for 44.3 at % carbon.

Simonellites

This is a colorless to white Simonellite on fossil wood. Credit: Thomas Witzke / Abraxas-Verlag.

Def. an "orthorhombic-dipyramidal white mineral containing carbon and hydrogen [C₁₉H₂₄]" is called a simonellite.

Simonellites have about 44.2 at % carbon.

Hartites

Hartite locality is Oberhart near Gloggnitz, Austria. Credit: Ra'ike.

Hartites have about 37 at % carbon with a formula of C₂₀H₃₄.

Fichtelites

Def. a "rare white monoclinic organic mineral, [7-isopropyl-1,4a-dimethyl-dodecahydro-1H-phenanthrene (C₁₉H₃₄)], found in fossilized wood" is called a fichtelite.

Also, occurs in "fossilized pine wood from a peat bog; in organic-rich modern marine sediment."

Fichtelites have about 35.8 at % carbon.

Evenkites

Aggregates of colourless evenkite in vugs of altered andesite, where the evenkite was confirmed by PXRD. Credit: Martin Stevko.

Evenkite has about 32.4 at % carbon in its formula: (CH₃)₂(CH₂)₂₂.

Hypotheses

Main resource: Hypotheses

1. The easiest resource for specific elements is as a native element mineral.

See also

• Carbonates
• Carbonites
• Carbons
• Organic minerals
• Siliconides