Chrysocolla
Chrysocolla | |
---|---|
niery chrysocolla from the L'Etoile du Congo mine near Lubumbashi, Katanga, Democratic Republic of the Congo | |
General and classification | |
chemical formula | Cu 4 H 4 [(OH) 8 | Si 4 O 10 ] • n H 2 O |
Mineral class (and possibly department) |
Silicates and Germanates |
System no. to Strunz and to Dana |
9.ED.20 ( 8th edition : VIII / E.21) 0374.03.02.01 |
Similar minerals | Azurite , malachite , dioptase , turquoise |
Crystallographic Data | |
Crystal system | orthorhombic |
Crystal class ; symbol | not known |
Physical Properties | |
Mohs hardness | 2 to 4 |
Density (g / cm 3 ) | 1.93 to 2.4 |
Cleavage | no |
Break ; Tenacity | shell-like, uneven |
colour | blue and green in different compositions and shades |
Line color | White |
transparency | translucent to opaque |
shine | Glass gloss, greasy gloss, earthy matt |
Crystal optics | |
Refractive indices |
n α = 1.575 to 1.585 n β = 1.597 n γ = 1.598 to 1.635 |
Birefringence | δ = 0.023 to 0.050 |
Optical character | uniaxial positive |
Pleochroism | colorless - pale blue-green |
Chrysocolla , as Chrysokolla , Pebble copper , Kieselmalachit , copper gravel , copper green or Berggrün known is a common mineral from the mineral class of " Silicate and Germanates ". It crystallizes in the orthorhombic crystal system with the approximate chemical composition Cu 4 H 4 [(OH) 8 | Si 4 O 10 ] · n H 2 O and developed predominantly micro- crystalline , low one to traubige, stalactitic or granular to earthy mineral aggregates and crusty Overlays in a blotchy, blue-green color of various shades.
Etymology and history
Chrysocolla has been known since ancient times . The name is a combination of the Greek words χρυσός chrysos (gold) and κόλλα kolla (glue), meaning gold glue, as it was used as an aid in ancient goldsmithing, granulation .
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the chrysocolla still belongs to the division of " ring silicates (cyclosilicates)", where it forms a separate group with dioptase .
Since the complete revision of Strunz'schen systematic mineral in the 9th edition is the chrysocolla in the department of " phyllosilicates (phyllosilicates)" and there due to its crystal structure in the subsection "phyllosilicates (phyllosilicates) with kaolinite, composed of tetrahedral or octahedral networks" sorted. The mineral can be found there together with allophane , bismuth ferrite , chapmanite , imogolite and neotokite in the unnamed group 09.ED.20 .
The systematics of minerals according to Dana , which is common in the English-speaking world , also assigns the chrysocolla to the layered silicate department, but in this system the departments are already subdivided more precisely according to the structural structure and the mineral can be found accordingly in the specific department of layered silicates with modulated layers and there in the subdivision of layered silicates: modulated layers with connected strips . Chrysocolla can be found there as the only member of the unnamed group 74.03.02
Crystal structure
Chrysocolla crystallizes orthorhombically in an unspecified space group with the 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 2 formula units per unit cell .
properties
Chrysocolla is infusible in front of the soldering tube. It dissolves in hydrochloric acid and separates out powdered SiO 2 .
Education and Locations
Chrysocolla is a typical secondary mineral that emerges from other copper minerals through transformation (weathering, metamorphosis) . Together with azurite , malachite , cuprite and others, it is therefore mainly found in copper deposits .
Chrysocolla has so far (as of 2010) been found at more than 2,700 sites worldwide, including Broken Hill in Australia , Saida / Kreischa , Schneeberg (Saxony), Lauterberg and Kupferberg in Germany , Mednorudnyansk / Ural in the Russian Federation and Bisbee and Morenci in the USA .
use
As a raw material
In local accumulation, chrysocolla is used as copper ore . As a copper mineral, it has a toxic effect on certain living beings and is therefore used, among other things, as an anti- fouling additive for underwater paints, especially in shipbuilding .
As a gem
Chrysocolla is a popular gemstone because of its lively blue-green spotted surface . However, due to its low hardness, water retention and the tendency to crack, the stone reacts very sensitively to major warming and physical and chemical stress.
Two very similar mineral adhesions ( rocks ) are also commercially available: Chrysocolla quartz is a mixture of chrysocolla and quartz . Eilat stone is one of chrysocolla, malachite and turquoise . Another misleading trade name is Azulita for an intergrowth of chrysocolla, azurite, malachite, cuprite and dioptase.
See also
literature
- Hugo Blümner : Chrysocolla 2 . In: Paulys Realencyclopadie der classischen Antiquity Science (RE). Volume III, 2, Stuttgart 1899, Col. 2515.
- Martin Okrusch, Siegfried Matthes: Mineralogy: An introduction to special mineralogy, petrology and deposit science . 7th edition. Springer Verlag, Berlin, Heidelberg, New York 2005, ISBN 3-540-23812-3 , pp. 107 .
- Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, Stuttgart 1978, ISBN 3-432-82986-8 , p. 713 .
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 259 .
- Walter Schumann: Precious stones and gemstones. All species and varieties in the world. 1600 unique pieces . 13th revised and expanded edition. BLV Verlags GmbH, Munich et al. 2002, ISBN 3-405-16332-3 .
Web links
- Copper green . In: Meyers Konversations-Lexikon . 4th edition. Volume 10, Verlag des Bibliographisches Institut, Leipzig / Vienna 1885–1892, p. 325.
- Mineral Atlas: Chrysocolla (Wiki)
- Handbook of Mineralogy - Chrysocolla (English, PDF 70.5 kB)
- Webmineral - Chrysocolla (English)
- Gem Etiquette - Chrysocolla (a)
Individual evidence
- ↑ a b Chrysocolla at mindat.org (English)
- ^ A b 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. 676 .
- ↑ Mindat - Localities for Chrysocolla