Brochantite
| Brochantite | |
|---|---|
 (size: 2.3 cm × 2.0 cm × 0.8 cm) |
|
| General and classification | |
| chemical formula | Cu 4 [(OH) 6 | (SO 4 )] |
|
Mineral class (and possibly department) |
Sulphates (selenates, tellurates, chromates, molybdates, tungstates) |
|
System no. to Strunz and to Dana |
7.BB.25 ( 8th edition : VI / B.01) 01/30/03/01 |
| Crystallographic Data | |
| Crystal system | monoclinic (pseudo-orthorhombic) |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | P 2 1 / a (No. 14, position 3) |
| Lattice parameters |
a = 13.09 Å ; b = 9.84 Å; c = 6.01 Å β = 103.3 ° |
| Formula units | Z = 4 |
| Twinning | generally according to {100} |
| Physical Properties | |
| Mohs hardness | 3.5 to 4 |
| Density (g / cm 3 ) | measured: 3.97; calculated: 4.09 |
| Cleavage | completely after {100} |
| Break ; Tenacity | shell-like to uneven |
| colour | light green, emerald green, blue green, black green |
| Line color | light green |
| transparency | transparent to translucent |
| shine | Glass gloss, pearlescent gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.728 n β = 1.771 n γ = 1.800 |
| Birefringence | δ = 0.072 |
| Optical character | biaxial negative |
| Axis angle | 2V = 72 ° (measured); 76 ° (calculated) |
| Other properties | |
| Chemical behavior | soluble in acids and ammonia |
Brochantite (also known as blanchardite ) is a frequently occurring mineral from the mineral class of " sulfates (selenates, tellurates, chromates, molybdates, wolframates)". It crystallizes in the monoclinic crystal system with the chemical composition Cu 4 [(OH) 6 | (SO 4 )] and is therefore chemically a copper sulfate with additional hydroxide ions .
Brochantite usually develops long prismatic to needle-like crystals and twins with a pseudo-orthorhombic appearance of several centimeters in length, but also occurs in the form of kidney-grape, granular to massive aggregates or parallel-rayed crusts. The surfaces of the transparent to translucent crystals have a glass-like sheen , whereas the cracked surfaces have a more mother-of-pearl shimmer . The color fluctuates between light green, emerald green, blue-green and black-green, but the line color always shows a light green.
Etymology and history
Was first discovered in 1824 in the Brochantit copper - deposit "Mednorudjanskoje" at Nischni Tagil / Yekaterinburg in the Russian oblast Swerdlowsk described by and Armand Lévy (1795-1841), of the minerals by André Brochant de Villiers named (1772-1840).
classification
In the old (8th edition) and new systematics of minerals according to Strunz (9th edition) , brochantite belongs to the division of "anhydrous sulfates with foreign anions ". The new Strunz'sche mineral classification, however, subdivides here more precisely according to the size of the cations involved and the mineral is therefore correspondingly in the sub-section “With medium-sized cations”.
The systematics used in the English-speaking world of minerals according to Dana assigns brochantite to the division of " anhydrous sulfates with hydroxyl or halogen and the general composition (AB) m (XO 4 ) p Z q , where m: p> 2: 1 " .
Crystal structure
Brochantite crystallizes monoclinically in the space group P 2 1 / a (space group no. 14, position 3) with the lattice parameters a = 13.09 Å ; b = 9.84 Å; c = 6.01 Å and β = 103.3 ° as well as four formula units per unit cell .
properties
Brochantite dissolves in very dilute acids . When heated in a glass tube, brochantite releases sulfur dioxide and water, turning it black.
Brochantite is also soluble in aqueous ammonia solutions with the formation of a characteristic, deep blue tetraammine copper (II) complex. This process is mainly used when cleaning marble and limestone to remove the usually water-insoluble copper compounds such. B. azurite , malachite and brochantite from the stone, whereby the progress of the cleaning can be followed visually due to the change in color.
Education and Locations
Brochantite forms as a secondary mineral mainly under arid climatic conditions in the oxidation zone of copper ore deposits. Accompanying minerals are mainly antlerite and malachite , with which it is often confused, but also atacamite , azurite , calcite , caledonite , cerussite , chrysocolla , cuprite , cyanotrichite , linarite and tenorite .
Brochantite has already been proven to be a frequent mineral formation at many sites, with over 1500 sites being known to date (as of 2015). In addition to its type locality "Mednorudjanskoje", the mineral appeared in Russia in other places in the Sverdlovsk Oblast, as well as in a few places in Eastern Siberia (Aldan, Udokan), in the North Caucasus ( Adygeya ) and on the Kola Peninsula ( Chibinen ).
In Germany, Brochantit could be found in many places in the Black Forest in Baden-Württemberg, in some places in Franconia and in the Spessart in Bavaria, in the Hessian Odenwald and in the Richelsdorf Mountains , in many places in the Harz from Lower Saxony to Saxony-Anhalt such as Bad Lauterberg , Goslar , Sankt Andreasberg and Hasserode , in various places in the Eifel and Siegerland from North Rhine-Westphalia to Rhineland-Palatinate, in some places in the Saxon Ore Mountains and in a few places in Saarland, Schleswig-Holstein and Thuringia.
In Austria, brochantite has so far been found mainly in Carinthia , Salzburg ( Hohe Tauern , Schwarzleograben), Styria and Tyrol ( Brixlegg - Schwaz region ).
In Switzerland, the mineral appeared in some places in the canton of Graubünden and in many places in the Val d'Anniviers in the canton of Valais.
Other locations are in Afghanistan, Egypt, Algeria, the Antarctic, Argentina, Australia, Belgium, Bolivia, Brazil, Bulgaria, Chile, China, the Democratic Republic of the Congo, Finland, France, Greece, Greenland, India, Indonesia, Ireland, Iran, Iceland, the Isle of Man, Israel, Italy, Japan, Canada, Kazakhstan, Kyrgyzstan, Cuba, Laos, Luxembourg, Madagascar, Morocco, Mexico, Mongolia, Mozambique, Namibia, New Caledonia, New Zealand, Norway, Pakistan , Peru, Poland, Portugal, Romania, Zambia, Zimbabwe, Slovakia, Spain, South Africa, Taiwan, Tajikistan, Turkey, the Czech Republic, Hungary, Ukraine, the United Kingdom (UK) and the United States of America (USA) .
Brochantite could also be detected in rock samples from the Mid-Atlantic Ridge (Logatchev hydrothermal field).
See also
literature
- A. Lévy: On a new mineral substance in: The Annals of Philosophy Volume 8, October 1824, pp. 241–245 (English, PDF 345.3 kB )
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 139 .
- Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 601 .
Web links
- Mineral Atlas: Brochantite
- American Mineralogist Crystal Structure Database - Brochantite
- Handbook of Mineralogy - Brochantite (Mineral data sheet, English, PDF 65.5 kB)
Individual evidence
- ↑ Webmineral - Brochantite (English)
- ↑ a b c d 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. 371 .
- ↑ a b c Brochantite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 65.5 kB )
- ↑ a b c d e Mindat - Brochantite (English)
- ↑ Curtis P. Schuh: Annotated Bio-Bibliography of Mineralogy and Crystallography 1469-1919 - Lévy, Armand (English)
- ↑ FEAD GmbH: Removal of discolouration on natural stone surfaces . In: Stone Decay and Conservation, Leipzig, 2005.
- ↑ Mindat - Number of localities for Brochantit
- ↑ Find location list for brochantite in the Mineralienatlas and Mindat
- ↑ Mindat - Logatchev hydrothermal field location, Mid-Atlantic Ridge