Austinite

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Austinite
Austinite-Conichalcite-283277.jpg
Austinite (colorless) on Konichalcite (green) from the Gold Hill Mine (Western Utah Mine), Deep Creek Mountains, Utah, USA
General and classification
chemical formula CaZn [OH | AsO 4 ]
Mineral class
(and possibly department) 		Phosphates, arsenates and vanadates
System no. to Strunz
and to Dana 		8.BH.35 ( 8th edition : VII / B.26)
41.05.01.03
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-disphenoidic; 222
Space group P 2 1 2 1 2 1 (No. 19)Template: room group / 19
Lattice parameters a  = 7.51  Å ; b  = 9.04 Å; c  = 5.93 Å
Formula units Z  = 4
Frequent crystal faces {011}, {111}, {1 1 1}, {010} and many others
Physical Properties
Mohs hardness 4 to 4.5
Density (g / cm 3 ) measured: 4.13; calculated: 4.31
Cleavage good after {011}
Break ; Tenacity brittle
colour colorless, yellowish white, green, brown
Line color White
transparency transparent to translucent
shine weak diamond luster, silky luster on aggregates
Crystal optics
Refractive indices n α  = 1.759 (3)
n β  = 1.763 (3)
n γ  = 1.783 (3)
Birefringence δ = 0.024
Optical character biaxial positive
Axis angle 2V = measured: 47 °; calculated: 50 °

Austinite is a rarely occurring mineral from the mineral class of "phosphates, arsenates and vanadates" with the chemical composition CaZn [OH | AsO 4 ] and is therefore chemically a calcium - zinc - arsenate with additional hydroxide ions .

Austinite crystallizes in the orthorhombic crystal system and develops many different crystal and aggregate forms . In addition to leafy to prismatic crystals, there are also radial, kidney, bulbous and fibrous aggregates and crusty coatings. In addition, crystal twins often form , which show clear chirality ( enantiomorphism ), i.e. left or right-handedness of the crystal faces.

In its pure form, Austinite is colorless or white due to lattice construction defects or twinning. However, it can also appear yellowish-white, green or brown due to foreign admixtures.

Austinite and konichalcite form a seamless mixed series .

Etymology and history

Austinite was first discovered in 1935 in the " Gold Hill Mine" in the Deep Creek Mountains in Tooele County (Utah) in the USA and described by Lloyd W. Staples, who named the mineral after Austin Flint Rogers (1877-1957), an American mineralogist from Stanford University.

classification

In the meanwhile outdated, but still in use 8th edition of the systematics of minerals according to Strunz , the austinite belonged to the mineral class of "phosphates, arsenates and vandadates" and there to the department of "anhydrous phosphates with foreign anions ", where it belongs together with the lead mineral adelite and the other members Duftit , Gabrielsonit , Gottlobit , Cobaltaustinit , Konichalcit , Nickelaustinit and Tangeit formed the Adelitgruppe .

The systematics of minerals according to Strunz (9th edition) , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns Austinite to the class of "phosphates, arsenates and vandadates" and there in the department of "phosphates, etc." additional anions; without H 2 O “. This section is more precisely subdivided according to the size of the cations and according to the ratio of the additional anions to the phosphate (vanadate, arsenate) complex and the mineral is accordingly in the subdivision “with medium-sized and mostly large cations; (OH etc.): RO 4  = 1: 1 “. The still existing "Adelitgruppe" with the system no. 8.BH.35 was expanded to include the mineral arsenic .

The systematics of minerals according to Dana also assigns Austinite to the class of "phosphates (and relatives)", but there in the department of "anhydrous phosphates etc., with hydroxyl or halogen". Here, too, he is together with Adelite, Konichalcite, Austinite, Duftit-beta , Gabrielsonite, Tangeit, Nickelaustinite, Cobaltaustinite and Arsendescloizit in the "Adelite group" with the system no. 41.05.01 to be found within the sub-section of " anhydrous phosphates etc., with hydroxyl or halogen and the general formula (AB) 2 (XO 4 ) Z q ".

Crystal structure

Austinite crystallizes orthorhombically in the space group P 2 1 2 1 2 1 (space group no. 19) with the lattice parameters a  = 7.51  Å ; b  = 9.04 Å and c  = 5.93 Å and 4 formula units per unit cell . Template: room group / 19

Modifications and varieties

As Barthit a copper-containing, green is the variety of Austinit referred.

Education and Locations

Austinite (shiny silver-gray) and Talmessite (white) from the "Gold Hill Mine", Utah, USA

Austinite is a rare secondary mineral that forms in the oxidation zone of some arsenic-rich, metallic deposits . Accompanying minerals include adamin , limonite , quartz and talmessite .

As a rare mineral formation, Austinite could only be detected at a few sites, with around 90 sites being known to date (as of 2016). In addition to its type locality “Gold Hill Mine”, the mineral could also be found in Utah in the “Gold Chain Mine” near Mammoth in Juab County .

In Germany, Austinite occurred in the “Silberbrünnle” mine in the Haigerachtal near Gengenbach and in the “Michael” mine near Weiler near Reichenbach in Baden-Württemberg; near Bad Ems in the Rhineland-Palatinate part of the Lahn valley and in the St. Wolfgang and Maaßen pit near Schneeberg in the Saxon Ore Mountains region.

The only known sites in Austria so far are two slag heaps in the Hüttwinkltal (end of the Rauris valley , Hohe Tauern) in Salzburg.

Other sites are among others in South Australia ; in the Bolivian department of La Paz ; the Wraza Oblast in Bulgaria; the Región de Atacama of Chile; in the Inner Mongolia Autonomous Region in China; the Brittany and Languedoc-Roussillon in France; the Greek region of Lavrio ; Souss-Massa-Draâ in Morocco; the Mexican states of Chihuahua and Durango ; in Tsumeb and Grootfontein in Namibia; in the Kielc highlands of Poland; the Central Province of Zambia; in the Spanish regions of Andalusia and Catalonia ; in the Hungarian county of Borsod-Abaúj-Zemplén and in various regions of the US states of Arizona , California , Colorado , Nevada , New Jersey , New Mexico , Utah and Washington .

See also

literature

Web links

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

Individual evidence

  1. ↑ a b c d e Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  458 .
  2. ↑ Webmineral - Austinite (English)
  3. ↑ a b c d Austinite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 65.7 kB )
  4. ↑ a b c d e Mindat - Austinite (English)
  5. ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
  6. ↑ Mindat - Number of localities for Austinite
  7. ↑ Find location list for Austinite at [Mineralienatlas] and at Mindat