Atacamite
| Atacamite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Cu 2 Cl (OH) 3 |
|
Mineral class (and possibly department) |
Halides |
|
System no. to Strunz and to Dana |
3.DA.10a ( 8th edition : III / D.01) 01/10/01/01 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic-dipyramidal; 2 / m 2 / m 2 / m |
| Space group | Pnma (No. 62) |
| Lattice parameters | a = 6.03 Å ; b = 9.12 Å; c = 6.86 Å |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 3 to 3.5 |
| Density (g / cm 3 ) | measured: 3.745 to 3.776; calculated: 3.756 |
| Cleavage | completely after {010}, clearly after {101} |
| Break ; Tenacity | shell-like |
| colour | grass green, emerald green to black green |
| Line color | apple green |
| transparency | transparent to translucent |
| shine | Glass gloss to diamond gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.831 n β = 1.861 n γ = 1.880 |
| Birefringence | δ = 0.049 |
| Optical character | biaxial negative |
| Axis angle | 2V = 74 ° (calculated) |
| Pleochroism | weak: X = light green; Y = yellow green; Z = grass green |
| Other properties | |
| Chemical behavior | sensitive to strong acids, insensitive to weak acids, light, water |
Atacamite is a rather rare mineral from the mineral class of halides . It crystallizes in the orthorhombic crystal system with the composition Cu 2 Cl (OH) 3 , so it is chemically a copper - chlorine oxyhalide.
Atacamite mostly develops prismatic crystals with a predominantly needle-like to columnar habit up to about 10 centimeters in length, but can also be found in the form of radial, leafy, fibrous or granular to massive mineral aggregates . The surfaces of the transparent to translucent crystals have a glass-like to diamond-like sheen . Its color varies between grass green, emerald green and black green, its stroke color is described as apple green.
Etymology and history
Atacamite was first discovered by the explorer Dombey in the Chilean Atacama Desert . However, the mineral was initially known under various descriptive names such as copper sand or hydrochloric copper sand , green sand from Peru and copper horn ore (after Dietrich Ludwig Gustav Karsten , 1800).
The name of Atacamite, which is still valid today, was given to the mineral in 1802 by Johann Friedrich Blumenbach , who named it after its type of locality .
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the atacamite belonged to the department of "oxyhalides", where it was named after the "atacamite series" with the system no. III / D.01 and the other members Anthonyit , Belloit , Bobkingit , Botallackit , Calumetit , Gillardit , Haydeeit , Herbertsmithite , Hibbingit , Kapellasit , Kempit , Klinoatacamit , Korshunovskit , Melanothallit , Nepskoeit and Paratacamit formed.
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 atacamite in the expanded division of "oxyhalides, hydroxyhalides and related double halides". This is further subdivided according to the predominant metals in the compound, so that the mineral can be found according to its composition in the sub-section “With Cu etc., without Pb”, where it only belongs to the unnamed group 3 together with hibbingite and kempit . DA.10a forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the atacamite to the “halides” class and there to the “oxyhalides and hydroxyhalides”. Here it can be found together with Hibbingite, Gillardite and Haydeeit in the unnamed group 10.01.01 within the subdivision " Oxyhalides and hydroxyhalides with the formula A 2 (O, OH) 3 X q ".
Crystal structure
Atacamite crystallizes orthorhombically in the space group Pnam (space group no. 62, position 6) with the lattice parameters a = 6.03 Å ; b = 9.12 Å and c = 6.86 Å and 4 formula units per unit cell .
Modifications and varieties
Four natural modifications of the compound Cu 2 Cl (OH) 3 are known so far . In addition to the orthorhombic atacamite, these are the monoclinically crystallizing minerals botallackite and clinoatacamite as well as the trigonal paratacamite.
Education and Locations
Atacamite forms in the oxidation zone of sulfidic copper deposits under arid climatic conditions . It occurs less often as a sublimation product of volcanic gases . Atacamite is also found as a secondary mineral formation in slag from former ore smelting and in the patina of ancient bronzes .
The accompanying minerals include botallackite , brochantite , caledonite , cuprite , linarite and paratacamite. Under the influence of the atmosphere, atacamite slowly transforms into malachite and, in the presence of silica, into chrysocolla .
As a rather rare mineral formation, atacamite can sometimes be abundant at various sites, but overall it is not very common. Around 500 sites are known to date (as of 2012). In the type locality applicable Atacama Desert or the same Atacama was the mineral in many places be found as, among others, in the area of the volcano Cerro Negro in the province of Chañaral , Checo de Cobre , Tierra Amarilla and Zapallar (Chile) in the Province Copiapó and Vallenar in the province of Huasco . Atacamite was also found in many other regions of Chile.
Known due to extraordinary atacamite finds, among other things, Burra in South Australia, where the longest known crystals were found with around 10 centimeters. Well-formed crystals, several centimeters in size, were also found in the copper mines of Moona and Wallaroo . The crystals in Tsumeb in Namibia can reach a diameter of up to one centimeter .
In Germany, atacamite was found in the Clara mine in Baden-Württemberg, in the copper mines near Lichtenberg and Kupferberg as well as in the Berchtesgaden salt mine in Bavaria, in the slag fields of the copper works near Frankfurt-Heddernheim and Richelsdorf in Hesse, in the Julius hut Astfeld in Lower Saxony's Harz Mountains, in the Christian Levin and Pluto collieries in North Rhine-Westphalia and the Marsberg copper mines , in the slag dump of the “Virneberg” mine near Rheinbreitbach in Rhineland-Palatinate, in the Mansfeld basin in Saxony-Anhalt , in the “Lorenz Gegentrum” mine "At Halsbrücke and the" Deutschlandschacht "near Oelsnitz / Erzgeb. in Saxony and on the north coast of Heligoland in Schleswig-Holstein.
In Austria, only the “Haagen” mine near Webing in the Salzburg market town of Abtenau and the “ Silberberg ” (Stockerstollen) in the Tyrolean municipality of Brixlegg - Rattenberg are known to be sites.
The only known place of discovery in Switzerland so far are the salt mines near Bex in the canton of Vaud.
Other sites are found in the Antarctic, Argentina, Bolivia, China, the Democratic Republic of the Congo, France, Greece, Canada, India, Iran, Ireland, Isle of Man, Italy, Japan, Jordan, Kazakhstan, Mexico, New Zealand, Norway , Peru, Portugal, Russia, Slovakia, Spain, South Africa, Tonga, Turkmenistan, Ukraine, Hungary, Uzbekistan, the United Kingdom, the United States of America (USA) and Vietnam.
Atacamite could also be detected in rock samples from the Mid-Atlantic Ridge and the Pacific Ocean , more precisely from the Manus Basin of the Bismarck Sea and from the East Pacific Ridge .
use
Atacamite is of little importance as a copper ore.
In October 2002 Helga Lichtenegger and her colleagues from the University of California, Santa Barbara found copper in the four tooth-like jaws of the predatory and poisonous "bloodworm" Glycera dibranchiata , which is incorporated in the form of the mineral atacamite, and published their find in the journal Science .
See also
literature
-
XVII. Mineralogical remarks on the arsenic acid, hydrochloric acid and phosphoric acid copper by Mr. Oberbergrath DCG Karsten, in: The Society of Friends of Natural Research in Berlin, new writings , Volume 3, Berlin 1801 ( p. 288-306 in the Google book search)
- II. The real hydrochloric acid copper (with analyzes by Rochefoucaud, Berthollet and Proust from p. 303) in the Google book search
- Franz Ambrosius Reuss: copper sand . In: Textbook of Mineralogy according to Mr. OBR Karsten Mineralogical Tables Executed . Vol. 2. Friedrich Gotthold Jacobder, Leipzig 1803, p. 486-493 ( limited preview in Google Book Search [accessed September 26, 2019] Reissued by Forgotten Books, 2018, ISBN 978-0366964291 ).
- JF Blumenbach: L'atacamit, sable vert d'Atacama . In: Manuel D'Histoire Naturelle . tape 2 . Soulange Artaud, Paris 1803, p. 348–349 ( Online [PDF; 109 kB ; accessed on February 19, 2018]).
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 493 (first edition: 1891).
Web links
- Mineral Atlas: Atacamite (Wiki)
- American Mineralogist Crystal Structure Database - Atacamite (English, 1949 and 1986)
- Mineral Lexicon - Atacamite
Individual evidence
- ↑ a b c Franz Ambrosius Reuss: Textbook of Mineralogy: based on Mr. OBR Karsten mineralogical tables executed , Leipzig 1803 in the Google book search
- ↑ a b c Dietrich Ludwig Gustav Karsten : Tabular overview of the mineralogically simple fossils . In: Mineralogical tables with reference to the latest discoveries . Heinrich August Rottmann, Berlin 1800, p. 46–46 ( Online [PDF; 1.9 MB ; retrieved on February 19, 2018] Order: copper, genus: copper sand).
- ↑ JF Blumenbach: L'atacamit, sable vert d'Atacama . In: Manuel D'Histoire Naturelle . tape 2 . Soulange Artaud, Paris 1803, p. 348–349 ( Online [PDF; 109 kB ; accessed on February 19, 2018]).
- ↑ Hans Lüschen: The names of the stones. The mineral kingdom in the mirror of language . 2nd Edition. Ott Verlag, Thun 1979, ISBN 3-7225-6265-1 , p. 178 .
- ↑ Webmineral - Atacamite (English)
- ^ A b c 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. 171 .
- ↑ a b c d Atacamite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( Online [PDF; 70 kB ; accessed on February 19, 2018]).
- ↑ a b c d e f Mindat - Atacamite (English)
- ↑ IMA / CNMNC List of Mineral Names (2012; PDF; 8.9 MB)
- ↑ a b J. F. Blumenbach: Handbuch der Naturgeschichte , 6th edition, Frankfurt and Leipzig 1802, p. 653 in the Google book search
- ^ A b Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 337-339 .
- ↑ Petr Korbel, Milan Novák: Mineral Encyclopedia (= Dörfler Natur ). Nebel Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 68 .
- ↑ a b Mindat - localities for atacamite
- ↑ Bild der Wissenschaft: Stahlharte Biters: Bristle worms have metal in their jaws by Ute Kehse, July 29, 2003 (last accessed on February 19, 2018)