Chrysocolla

Chrysocolla, also known as Chrysokolla, Pebble copper, Kieselmalachit, copper pebbles, copper or green mountain green, is a commonly occurring mineral from the mineral class of " Silicate and germanate ". It crystallizes in the orthorhombic crystal system with the approximate chemical composition Cu4H4 [( OH) 8 | Si4O10 ] · n H2O and developed predominantly microcrystalline, low one to racemose, stalactitic or granular to earthy mineral aggregates and crusty coatings in mottled, blue-green color of various shades.

Special Features

Chrysocolla is infusible before the blowpipe. In hydrochloric acid it dissolves and separates it from powdered SiO2.

Etymology and history

Chrysocolla has been known since ancient times. The name is a combination of two Greek words χρυσός chrysos ( gold) and κόλλα kolla (sticking), so mutatis mutandis Goldleim since it as an aid in the ancient goldsmith, granulation, served.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the chrysocolla still belongs to the department of the " ring silicates ( cyclo- silicates) ", where it forms a separate group together with the Dioptas.

Since the full review of the Strunz'schen Mineral classification in the 9th edition of chrysocolla in the department is the " layer silicates ( phyllosilicates ) " and there due to its crystal structure in the subdivision " layered silicates ( phyllosilicates ) with kaolinite layers composed of tetrahedral or octahedral networks " sorted. The mineral can be found there along with allophane, Bismutoferrit, Chapmanit, Imogolith and Neotokit in the unnamed group 09.ED.20.

The commonly used in English-speaking classification of minerals according to Dana assigns the chrysocolla also in the Department of phyllosilicates, but in this system already the departments precision divided by the geological structure and the mineral is found according to the specific department of the phyllosilicates with modulated layers and there in the subdivision of the layer silicates: modulated layers with joined strips. Chrysocolla is found there, the only member of the unnamed group 74.03.02

Education and Locations

Chrysocolla is a typical secondary mineral that by converting ( weathering, metamorphism ) from other copper minerals is apparent. Together with azurite, malachite, cuprite and other finds, therefore, primarily in copper deposits.

Worldwide, chrysocolla so far (as of 2010) are detected in more than 2,700 localities, so among other things in Broken Hill in Australia, Saida / Kreischa, Schneeberg (Saxony), Loud Mountain and Copper Mountain in Germany, Mednorudnyansk / Ural in the Russian Federation and Bisbee Morenci and in the USA.

Crystal structure

Chrysocolla crystallizes in the orthorhombic a unspecified space group with lattice parameters a = 5.72 to 5.92 Å; b = 17.7 to 18.0 Å and c = 8.00 to 8.28 Å and two formula units per unit cell.

Use

As a raw material

For local accumulation Chrysocolla serves as copper ore. The copper mineral, it is toxic to certain organisms and is therefore used, among other things as an antifouling additive for underwater coatings especially in shipbuilding.

As a gemstone

Chrysocolla is because of its bright blue - green spotted surface a popular and relatively inexpensive gemstone. However, the stone reacts due to its low hardness, water retention and cracking very sensitive to greater warming as well as physical and chemical stress.

Commercially also two very similar Mineralverwachsungen ( rocks ) are available. Chrysokollquarz is a mixture of chrysocolla and quartz and Eilatstein is one of chrysocolla, malachite and turquoise. Another deceptive trade name is Azulita for an intergrowth of chrysocolla, azurite, malachite, cuprite, Dioptas.