Kleinit

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Kleinit
Kleinite-klein06c.jpg
Dark yellow Kleinit crystal lawn from the McDermitt Mine, Nevada, USA ( overall size : 9.8 cm × 6.4 cm × 3.8 cm)
General and classification
chemical formula (Hg 2 N) (Cl, SO 4 ) • nH 2 O
Mineral class
(and possibly department) 		Halides
System no. to Strunz
and to Dana 		3.DD.35 ( 8th edition : III / D.06)
04/10/03/01
Crystallographic Data
Crystal system hexagonal
Crystal class ; symbol dihexagonal-dipyramidal; 6 / m 2 / m 2 / m
Room group (no.) P 6 3 / mmc (No. 194)
Lattice parameters a  = 6.76  Å ; c  = 11.07 Å
Formula units Z  = 2
Frequent crystal faces {10 1 0}, {20 2 1}, and {0001}
Physical Properties
Mohs hardness 3.5 to 4
Density (g / cm 3 ) measured: 7.9 to 8.0; calculated: [7.87]
Cleavage indistinct after {0001}, imperfect after {1010}
Break ; Tenacity uneven; brittle
colour light yellow, canary yellow, orange, also zoned
Line color sulfur yellow
transparency transparent to translucent
shine Diamond luster (pure yellow varieties) to fat luster (orange varieties)
Crystal optics
Refractive indices n ω  = 2.190
n ε  = 2.210
Birefringence δ = 0.020
Optical character uniaxial negative, uniaxial positive ≥ 130 ° C, isotropic ≥ ≈ 190 ° C
Axis angle 2V = up to 80 °
Other properties
Chemical behavior soluble in HCl , HNO 3 , NH 4 Br
Special features Photochromism

Kleinite is a very rarely occurring mineral from the mineral class of " halides ". It crystallizes in the hexagonal crystal system with the chemical composition (Hg 2 N) (Cl, SO 4 ) · nH 2 O, so it is a hydrous mercury - nitrogen - chloride that structurally belongs to the double halides. The element chlorine in the round brackets and the sulphate anion SO 4 can represent each other in the formula ( substitution , diadochy), but are always in the same proportion to the other components of the mineral.

Kleinite is transparent to translucent and only develops small, isometric to short prismatic crystals of up to three millimeters in length and is usually found in the form of "crystal turf" and crusty coatings on other minerals or bedrock. In its pure form, Kleinit ranges from light yellow to canary or sulfur yellow in color. It can also take on an orange color through the addition of mercury oxide , and zoned crystals with a yellow core and an orange rim are also known. The gloss on the crystal surfaces ranges from a rather dull, greasy sheen in the case of orange varieties to a strong diamond shine in the case of purely yellow varieties.

With a Mohs hardness of 3.5 to 4, Kleinite is one of the medium-hard minerals that, like the reference mineral fluorite (4), can be easily scratched with a pocket knife .

Special properties

Kleinit is positive photochromic , i.e. in daylight its color intensifies and in the dark it returns to its original color.

The optical property of the birefringence of Kleinite is temperature dependent. The mineral is uniaxially negative at normal temperature, uniaxially positive when heated to over 130 ° C and uniaxially positive when heated to over 190 ° C.

Kleinit dissolves only with difficulty in cold hydrochloric acid (HCl), but leaves no residue in warm hydrochloric and nitric acid (HNO 3 ). In ammonium bromide (NH 4 dissolved Br) produced ammonia (NH 3 ).

Etymology and history

Kleinite was first discovered on a mineral sample from the mercury deposit near Terlingua in Brewster County of the US state of Texas , which was initially incorrectly labeled Terlinguaite . Arthur Sachs received this sample for closer examination from Carl Hintze, who at the time was director of the Krantz mineral office. Sachs published the results of his research on the new mineral in 1905 in the "Meeting reports of the Royal Prussian Academy of Sciences" and suggested the name Kleinit in honor of the German professor of mineralogy Carl Klein (1842-1907).

Type material of the mineral is stored at Harvard University in Cambridge, Massachusetts and the National Museum of Natural History in Washington, DC (Catalog No. 86639-86641, 86647) in the United States.

classification

Already in the outdated but still partially in use 8th edition of the mineral classification by Strunz of Kleinit belonged to the mineral class of "halides" and then to the Department of "oxyhalides" where he along with Aurivilliusit , Comancheit , Eglestonit , Gianellait , Hanawaltit , Kadyrelit , Mosesite , pinchite , poyarkovite , tedhadleyite , terlinguacreekite , terlinguaite , vasilyevite the "terlinguaite-eglestonite group" with the system no. III / D.06 .

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), classifies the Kleinit in the expanded division of "Oxyhalides, Hydroxyhalides and related double halides". However, this is further subdivided according to the predominant cations in the compound , so that the mineral can be found according to its composition in the subsection "with Hg", where it is the only member of the unnamed group 3.DD.35 .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the minerals to the “halides” class and there to the “oxyhalides and hydroxyhalides”. Here he is the only member of the unnamed group 04/10/03 within the subdivision “ 04/10 Oxihalides and hydroxyhalides with the formula A 2 (O, OH) X q ”.

Education and Locations

Sulfur yellow kleinite crystals from the McDermitt Mine, Nevada, USA (field of view 4 mm)
Rare find well-developed, needle-like kleinit crystals on quartz from the McDermitt mine (size: 5.3 cm × 4 cm × 4 cm)

Kleinit forms in the oxidation zone of hydrothermally formed mercury deposits . In addition to other mercury minerals such as montroydite , mosesite, calomel and terlinguaite, barite , calcite and gypsum , among others , can also occur as accompanying minerals .

So far (as of 2014) the mineral could only be detected in a few samples from less than 10 locations. In addition to its type locality Terlingua and the nearby Mariposa Mine ( California Mountain Mine ) in Texas, Kleinit was also found in the McDermitt mercury mine near Opalite in Humboldt County (Nevada) in the United States and on the Moschellandsberg near Obermoschel (Rhineland-Palatinate) in Germany.

Crystal structure

Kleinit crystallizes hexagonally in the space group P 6 3 / mmc (space group no. 194) with the lattice parameters a  = 6.76  Å and c  = 11.07 Å as well as two formula units per unit cell .

See also

literature

  • A. Sachs: The Kleinit, a hexagonal mercury oxychloride from Terlingua, Texas. In: Session reports of the Royal Prussian Academy of Sciences. 1905, pp. 1091-1094 ( PDF 250.6 kB )

Web links

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

Individual evidence

  1. ↑ a b IMA / CNMNC List of Mineral Names; March 2014 (PDF 1.5 MB)
  2. ^ A b c 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.  181 .
  3. ↑ a b c d e f g Kleinite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF kB )
  4. ↑ A. Sachs: The Kleinit, a hexagonal mercury oxychloride from Terlingua in Texas. In: Session reports of the Royal Prussian Academy of Sciences. 1905, p. 1094 ( PDF 250.6 kB )
  5. ↑ a b Mindat - Kleinite
  6. ↑ a b Mineralienatlas: Kleinit
  7. ↑ worldcat.org - Arthur Sachs: The Kleinit, a hexagonal mercury oxychloride from Terlingua in Texas
  8. ↑ A. Sachs: The Kleinit, a hexagonal mercury oxychloride from Terlingua in Texas. In: Session reports of the Royal Prussian Academy of Sciences. 1905, pp. 1091-1094 ( PDF 250.6 kB )
  9. ↑ Find location list for Kleinit in the Mineralienatlas and in Mindat