Greenockite
| Greenockite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | CdS |
|
Mineral class (and possibly department) |
Sulphides, sulphosalts - metal: sulfur, selenium, tellurium = 1: 1 |
|
System no. to Strunz and to Dana |
2.CB.45 ( 8th edition : II / C.13) 08/02/07/02 |
| Crystallographic Data | |
| Crystal system | hexagonal |
| Crystal class ; symbol | dihexagonal-pyramidal; 6 mm |
| Space group | P 6 3 mc (No. 186) |
| Lattice parameters | a = 4.14 Å ; c = 6.71 Å |
| Formula units | Z = 2 |
| Twinning | often multiple, twin level {11 2 2} |
| Physical Properties | |
| Mohs hardness | 3 to 3.5 |
| Density (g / cm 3 ) | measured: 4.82; calculated: 4.824 |
| Cleavage | imperfect after {0001}, clearly after {11 2 2}> |
| Break ; Tenacity | shell-like |
| colour | brownish, yellow, greenish, orange, red |
| Line color | yellow-orange to brick-red |
| transparency | translucent to opaque |
| shine | Diamond gloss to resin gloss |
| Crystal optics | |
| Refractive indices |
n ω = 2.529 n ε = 2.506 |
| Birefringence | δ = 0.023 |
| Optical character | uniaxial negative (uniaxial positive at wavelengths from red to blue-green) |
| Pleochroism | weak |
| Other properties | |
| Chemical behavior | dissolves in acid with evolution of hydrogen sulfide gas to |
| Special features | yellow to orange fluorescence |
Greenockite (outdated cadmium blende ) is a rather seldom occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the hexagonal crystal system with the chemical composition Cd S , so it is chemically a cadmium sulfide .
Greenockite is usually found in the form of earthy, powdery or crusty coatings, but rarely also forms small, hemimorphic , pyramidal crystals up to about three centimeters in size. The translucent to opaque crystals vary in color from yellow-orange to brick-red , depending on the amount of foreign matter, and have a resin-like to diamond-like sheen on the surface .
Etymology and history
Greenockite is named after Charles Cathcart, 2nd Earl Cathcart , then better known as Lord Greenock, on whose land the mineral was first found in 1840. The exact type locality is the Bishopton Tunnel near Bishopton (Renfrewshire) in Scotland .
Greenockite was first described in 1840 by Robert Jameson (1774-1854), the chemical analysis was carried out by Arthur Connell .
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the greenockite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfides with the molar ratio of metal: sulfur, selenium, tellurium = 1: 1", where together with Cadmoselit , Matrait (discredited 2006), Rambergit and Wurzit (Wurtzit-2H) he created the "Wurtzit series" with the system no. II / C.13 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 Greenockite in the category of “Metal sulfides with a molar ratio of M: S = 1: 1 (and similar)”. However, this is further subdivided according to the predominant metals in the compound, so that the mineral can be found in the sub-section "with zinc (Zn), iron (Fe), copper (Cu), silver (Ag) etc." according to its composition where, together with cadmoselite, rambergite and root, the "wurtzite group" with the system no. 2.CB.45 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns greenockite to the class of "sulfides and sulfosalts" and there to the category of "sulfide minerals". Here it is also part of the " Wurtzit group (hexagonal: P6 3 mc) " with the system no. 08/02/07 within the subsection of "Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 1: 1".
Crystal structure
Greenockite crystallizes hexagonally in the space group P 6 3 mc (space group no. 186) with the lattice parameters a = 4.14 Å and c = 6.71 Å as well as two formula units per unit cell .
The crystal structure equivalent of the Greenockit of wurtzite , thus composed CdS 4 - tetrahedrons together. One cadmium atom is surrounded by four sulfur atoms and vice versa. The interconnected tetrahedra are layered in a hexagonal arrangement.
Modifications and varieties
Greenockite is one of two modifications of cadmium sulfide . The second is the cubic crystallizing hawleyite .
Education and Locations
Greenockite is a typical secondary mineral , so it is formed by weathering or metamorphosis from sphalerite, among other things, and coats it in a crusty manner. Massive encrustations can also be found in cavities in volcanic rocks. Accompanying minerals are mainly calcite , galena , prehnite , sphalerite and various zeolites . As pyramidal crystals with a six-sided base, it forms mainly on ore veins .
As a rather rare mineral formation, greenockite can sometimes be abundant at various locations, but overall it is not very common. Around 600 sites are known to date (as of 2015).
Locations include Llallagua in Bolivia , Příbram in the Czech Republic , the Tsumeb Mine in Namibia , the Bleiberg in Austria , Renfrew in Scotland , the Empire Mines in Joplin Field, Jasper Co. , Missouri , and other pits in the Tri-State District ( Missouri, Oklahoma , Kansas ) in the United States .
use
In addition to monteponite and otavite, greenockite is an important cadmium mineral, but despite the 77.8% cadmium content, the mineral finds are too small to serve as ore. Cadmium is obtained as a by-product of zinc extraction.
It has been suggested, but not yet proven, that greenockite was used as a pigment 2000 years ago .
See also
literature
- Martin Okrusch, Siegfried Matthes: Mineralogy . 7th edition. Springer Verlag, Berlin 2005, ISBN 3-540-23812-3
- Stefan Weiß: The large Lapis mineral directory . 4th edition. Christian Weise Verlag, Munich 2002, ISBN 3-921656-17-6
- Edition Dörfler: Mineralien Enzyklopädie , Nebel Verlag, ISBN 3-89555-076-0
- Walter Schumann: Precious stones and gemstones . 13th edition. BLV Verlags GmbH, 1976/1989, ISBN 3-405-16332-3
Web links
- Mineral Atlas: Greenockite (Wiki)
- RRUFF Database-of-Raman-spectroscopy - Greenockite (English)
- American-Mineralogist-Crystal-Structure-Database - Greenockite (English)
- Webmineral - Greenockite (English)
Individual evidence
- ↑ a b c d Greenockite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 60 kB ; accessed on April 13, 2018]).
- ^ A b 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. 82 .
- ↑ a b c Mindat - Greenockite (English)
- ^ Robert Jameson: Notice of greenockite, a new mineral species of the order blende . In: The Edinburgh New Philosophical Journal . tape 28 , 1840, p. 390–292 ( rruff.info [PDF; 221 kB ; accessed on April 13, 2018]).
- ↑ Mindat - Number of localities for Greenockit (English)
- ↑ Find location list for Greenockit in the Mineralienatlas and Mindat
- ^ Kremer pigments - cadmium colors