Hartite

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Hartite
Hartite - Mineralogical Museum Bonn1.jpg
Hartit from Oberhart near Gloggnitz , Austria
General and classification
other names

Josen

chemical formula C 20 H 34
Mineral class
(and possibly department) 		Organic compounds
System no. to Strunz
and to Dana 		10.BA.10 ( 8th edition : II / B.15)
03/50/02/02
Crystallographic Data
Crystal system triclinic
Crystal class ; symbol triklin-pedial; 1
Room group (no.) P 1 (No. 1)
Lattice parameters a  = 11.41  Å ; b  = 20.95 Å; c  = 7.41 Å
α  = 93.9 °; β  = 100.7 °; γ  = 80.5 °
Formula units Z  = 4
Physical Properties
Mohs hardness 1
Density (g / cm 3 ) measured: 1.036 to 1.06; calculated: 1.064
Cleavage Well
Break ; Tenacity shell-like
colour colorless, white, gray, yellowish gray
Line color White
transparency translucent
shine Wax sheen, glass sheen on breakage and pearlescent on split surfaces
Crystal optics
Refractive indices n α  = 1.546
n β  = 1.555
n γ  = 1.587
Birefringence δ = 0.041
Optical character biaxial positive
Axis angle 2V = 57 ° (measured)

Hartite (also Josen ) is a very rare mineral from the mineral class of organic compounds . It crystallizes in the triclinic crystal system with the empirical formula C 20 H 34 and from a chemical point of view belongs to the hydrocarbons .

Hartit usually develops peeled, flaky or massive aggregates with a waxy sheen on the surfaces. On fresh fracture surfaces this turns into glass luster and on cracked surfaces into pearlescent luster. In its pure form it is colorless and transparent. However, due to multiple refraction due to lattice construction defects or polycrystalline formation, it can also appear white and, due to foreign admixtures, take on a gray to yellowish-gray color, the transparency decreasing accordingly.

With a Mohs hardness of 1, Hartite is just as soft as the reference mineral talc and can be easily scratched with a fingernail. Its density fluctuates between 1.036 and 1.06 g / cm³ depending on the purity of the mineral and is therefore only slightly higher than that of water (1 g / cm³).

Etymology and history

The mineral was discovered and described in 1841 by Wilhelm Ritter von Haidinger , who, together with Count von Breuner, went on an excursion to the brown coal mine near Oberhart near Gloggnitz in Lower Austria. There he found several samples of a material similar to Scheererite (fossil resin), which, however, in contrast to this, does not form pronounced crystals, but rather masses similar to walrus and has a higher melting point. Scheererite already melts at 46 ° C, while Hartite only melts at around 71 to 71.5 ° C (according to Haidinger at around 74 °). Haidinger chose the name Hartit based on its type locality .

The type material of the mineral is kept in the Krahuletz Museum in Eggenburg , Lower Austria .

classification

In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , Hartit belonged to the department of "nitrogen-free hydrocarbons", where together with Dinit , Fichtelit , Flagstaffit , Karpathit , Kratochvílit , Hoelit , Idrialin , Ravatit , Refikit and Simonellit the unnamed Group IX / B.02 formed.

In the course of the reorganization of Strunz's mineral systematics , this department was given the general name hydrocarbons in the 9th edition, which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), and the mineral was assigned to the as yet unnamed sub-department BA , where it is the only member the also unnamed group 10.BA.10 forms.

The systematics of minerals according to Dana , which is predominantly used in the English-speaking world , assigns the Hartite to the sub-division of " Salts of organic acids (hydrocarbons) ", where together with Ravatite it belongs to the "Ravatite group" named after this mineral with the system no. 50.03.02 can be found.

Education and Locations

Hartite formed by leaching the Lignitschichten in lignite - deposits with organic solvents and it is this or adjacent found as corresponding to split or crack filling layers. The accompanying minerals include siderite and limonite .

So far (as of 2012), Hartit has been found at fewer than ten sites worldwide. In addition to the lignite mine near Oberhart in Lower Austria, the mineral was also found in Austria near Göriach and Oberdorf near Köflach in Styria.

Other sites are the "Castelnuovo Mine" near Santa Barbara in the municipality of Cavriglia , I Gulfi in the municipality of Chianni and Terni in Italy; Bílina in the Czech Republic and Edelény in Hungary.

Crystal structure

Hartite crystallizes triclinically in the space group P 1 (space group no. 1) with the lattice parameters a  = 11.41  Å , b  = 20.95 Å, c  = 7.41 Å, α = 93.9 ° β = 100.7 ° and γ = 80.5 ° as well as four formula units per unit cell .

The crystal structure of Hartit consists of four independent molecules of different configurations, but each with three carbon rings in the shape of a “chair” and one ring in the shape of an “envelope”.

See also

literature

Web links

Commons : Hartite  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d e f Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  722 .
  2. ↑ Webmineral - Hartite (English)
  3. ↑ a b c d John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Hartite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 64.3 kB )
  4. ↑ a b c d Mindat - Hartite (English)
  5. ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke , Stuttgart 1978, ISBN 3-432-82986-8 , pp.  799 (first edition: 1891).
  6. ↑ GA Kenngott: About the Piauzit von Tüffer and the Hartit von Rosenthal in Styria , in: Jahrb. Geol. VIL 1856, pp. 91–95 ( PDF 311 kB )
  7. ↑ zeno.org - Scheererit
  8. ↑ Mindat - Number of localities for Hartit