Atacamite
- Green sand from Peru
- Kupferhornerz
- Copper sand
- Copper emerald
- Salzkupfererz (after Werner)
- Muriate of copper and hydrochloric acid copper sand
Atacamit is a rarely occurring mineral from the mineral class of halides. It crystallizes in the orthorhombic crystal system with the composition Cu2Cl (OH ) 3, is so chemically seen a copper - chlorine oxyhalide.
Atacamit most developed prismatic crystals with predominantly acicular habit säuligem up to about 10 centimeters in length, but is also found in the form radialstrahliger, bladed, fibrous or granular to massive mineral aggregates. The surfaces of transparent to translucent crystals have a glass - to diamond-like gloss. Its color varies between grass Green, Emerald Green and Black Green, his stroke color is described as apple green.
Etymology and history
Atacamit was first discovered by the explorers Dombey in the Chilean Atacama desert. The mineral was known, however, initially under various descriptive terms such as, among others, copper sand or hydrochloric acid copper sand, Green sand from Peru and Kupferhornerz ( by Dietrich Ludwig Gustav Karsten, 1800).
His final name Atacamit received the mineral in 1802 by Johann Friedrich Blumenbach, who named it after its type locality.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the Atacamit belonged to the department of " oxyhalides " where he. Namesake as the " Atacamit series" with the System No. Formed III/D.01 and the other members Anthonyit, Belloite, Bobkingit, Botallackit, Calumetit, Gillardit, Haydeeit, Herbertsmithite, Hibbingit, Kapellasit, Kempit, Klinoatacamit, Korshunovskit, Melanothallit, Nepskoeit and paratacamite.
The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the Atacamit in the Advanced section of the " oxyhalides, hydroxyhalides and related double halides " one. This is also further divided according to the conditions prevailing in the interconnect metals, so that the mineral is found according to its composition in the subsection "With Cu, etc., without Pb" where it only together with Hibbingit and Kempit the unnamed group 3 forms. DA.10a.
The mainly common in English-speaking classification of minerals according to Dana assigns the Atacamit into the class of " halides " and there in the department of " oxyhalides and hydroxyhalides ". Here it is found together with Hibbingit, Gillardit and Haydeeit in the unnamed group 10:01:01 within the subdivision " oxyhalides and hydroxyhalides with the formula A2 (O, OH) 3XQ ".
Modifications and varieties
From the connection Cu2Cl (OH) 3 are known so far four natural modifications. In addition to the orthorhombic Atacamit these are still the monoclinic crystallizing minerals Botallackit and Klinoatacamit and the trigonal paratacamite.
Education and Locations
Atacamit formed in the oxidation zone of sulfide copper deposits under arid climatic conditions. More rarely it occurs as a sublimation product of volcanic gases. Also, as a secondary mineral formation in ore smelting slag former and in the patina of antique bronzes found sometimes Atacamit.
Accompanying minerals occur among others Botallackit, Brochantite, Caledonit, cuprite, and Linarit paratacamite. Under the influence of the atmosphere Atacamit slowly turn into malachite and in the simultaneous presence of silica in chrysocolla.
As a rather rare mineral formation Atacamit at different sites can indeed be abundant in some cases, overall it is not very common. So far (as of 2012) are considered to be known around 500 localities. In the current as type locality Atacama Desert or the same Región de Atacama, the mineral could be found in many places such as, among others, in the vicinity of the volcano Cerro Negro in the province Chañaral, Checo de Cobre, Tierra Amarilla and Zapallar (Chile) in the province Copiapó and Vallenar in the province Huasco. In addition, Atacamit still found in many other regions of Chile.
Known due to exceptional Atacamit - finds, among other things Burra in South Australia, where around 10 centimeters, the longest known crystals were revealed. Well -formed crystals of several centimeters in size were also found in the copper mines of Moona and Wallaroo. Up to a centimeter in diameter, the crystals can be reached in Tsumeb in Namibia.
In Germany Atacamit found among others in the Gruba Clara in Baden -Württemberg, in the copper mines at Lichtenberg and Copper Mountain as well as in the salt mine of Berchtesgaden in Bavaria, in the slag fields of the copper works at Frankfurt- Heddernheim and Richelsdorf in Hesse, in the Julius- hut at Astfeld in Lower Saxony Harz, in the North Rhine- Westphalian collieries Christian Levin and Pluto, and the copper mines of Mars mountain, in the slag heap of the pit " Virneberg " at neck bridge in Rhineland -Palatinate, in the Mansfeld basin, Saxony- Anhalt, in the Pit " Lorenz Gegentrum "and the" Germany shaft " in Oelsnitz / Erzgeb. in Saxony and on the north coast of Helgoland in Schleswig -Holstein.
In Austria, so far only the pit " Haagen " at Webing in the market town of salzburg Abtenau and the " Silver Mountain" ( Stocker tunnel ) in the Tyrolean municipality Brixlegg rats mountain.
The only known locality in Switzerland are the salt mines at Bex in Canton Vaud.
Other localities lie among other things in Antarctica, Argentina, Bolivia, China, the Democratic Republic of 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, Uzbekistan, the United Kingdom, the United States of America ( USA) and in Vietnam.
Even in rock samples from the Mid-Atlantic Ridge and in the Pacific Ocean, more specifically from the Manus Basin of the Bismarck Sea and the East Pacific Rise, Atacamit could be detected.
Crystal structure
Atacamit crystallizes in the orthorhombic space group Pnam ( Raumgruppen-Nr. 62) with the lattice parameters a = 6.03 Å; b = 9.12 Å and c = 6.86 Å and four formula units per unit cell.
Use
As copper Atacamit has little meaning.
In October 2002, found Helga light Egger and her colleagues from the University of California, Santa Barbara in the four tooth-like jaws of the predatory and toxic " blood worm " Glycera dibranchiata copper that as the mineral Atacamit is installed and published their discovery in the journal Science.