Boleit
| Boleit | |
|---|---|
 |
|
| General and classification | |
| chemical formula | KPb 26 Cu 24 Ag 9 (OH) 48 Cl 62 |
|
Mineral class (and possibly department) |
Halides |
|
System no. to Strunz and to Dana |
3.DB.15 ( 8th edition : III / D.12) 06/10/06/01 |
| Crystallographic Data | |
| Crystal system | cubic |
| Crystal class ; symbol | cubic-hexakisoctahedral |
| Room group (no.) | Pm 3 m (No. 221) |
| Lattice parameters | a = 15.29 Å |
| Formula units | Z = 1 |
| Frequent crystal faces | {111}, {011} |
| Physical Properties | |
| Mohs hardness | 3 to 3.5 |
| Density (g / cm 3 ) | measured: 5.054; calculated: 5.082 |
| Cleavage | completely after {001} |
| colour | intense blue, also blue-green in transmitted light |
| Line color | blue |
| transparency | translucent to opaque |
| shine | weak glass luster, pearlescent luster |
| Crystal optics | |
| Refractive index | n = 2.05 |
| Birefringence | none, as isotropic |
| Other properties | |
| Chemical behavior | soluble in water |
Boleit is a rarely occurring mineral from the mineral class of " halides ". It crystallizes in the cubic crystal system with the chemical composition KPb 26 Cu 24 Ag 9 (OH) 48 Cl 62 and develops almost exclusively translucent to transparent crystals with a cubic habit or combinations of cubic shapes. Boleit is often also found with cumengeit or pseudoboleit oriented ( epitaxially ) grown. The surfaces of the characteristic, intensely blue crystals have a faint glass sheen , whereas cleavage surfaces have a mother-of-pearl shimmer.
With a Mohs hardness of 3 to 3.5, Boleit, along with the reference mineral calcite, is one of the soft minerals that can be scratched with a copper coin.
Special properties
Boleit is water-soluble and must therefore be stored away from moisture.
Etymology and history
Boleit was first discovered in Santa Rosalía ( Boleó ) in the Mexican province of Baja California Sur and described in 1891 by François Ernest Mallard and Edouard Cumenge , who named the mineral after its type locality .
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the Boleit belonged to the mineral class of "halides" and there to the department of "oxyhalides", where together with bideauxite , chloroxiphite , cumengeit , diaboleit , hematophanite , pseudoboleit and yedlinite formed an independent group.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns the Boleit to the “halides” class, but in the extended division of “oxyhalides, hydroxyhalides and related double halides” " a. This department is also further divided according to prevailing in the connection metals, so that the mineral according to its composition in the subsection "With Pb, Cu, etc." is to find where it is the only member of the unnamed group 3.DB.15 forms .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Boleit to the class of "halides" and there in the also expanded division of "oxyhalides and hydroxyhalides". Here he is to be found as the only member of the unnamed group 10.06.01 within the sub-section " Oxyhalides and hydroxyhalides with the formula A m B n (O, OH) p X q ".
Education and Locations
Boleit forms as a secondary mineral by the reaction of chlorine compounds with primary sulphides in the oxidation zone of copper - deposits in arid climates . In addition to cumengeit and pseudoboleit, accompanying minerals include atacamite , anglesite , bideauxite , cerussite , caledonite , gypsum , leadhillite , matlockite , paratacamite , paralaurionite and phosgenite .
So far (as of 2011), Boleit has been identified at around 55 sites worldwide. In addition to its type locality Santa Rosalía ( Boleó ) in Baja California Sur, the mineral occurred in Mexico at Arizpe in Sonora. The largest Boleit cubes with an edge length of up to 3.5 cm were also found in Boleó.
The only previously known site in Germany is the slag dump of the Herzog-Julius-Hütte in Astfeld in the Harz Mountains in Lower Saxony.
Other locations are Broken Hill in Australia; the Chilean regions of Antofagasta and Tarapacá ; Poullaouen and Le Pradet in France; the Greek region of Attica ; Anarak in Iran ; the Italian province of Livorno ; several locations in England in the United Kingdom (Great Britain) and many locations in Arizona , California , Montana , Nevada, and Washington in the United States of America (USA).
Crystal structure
Boleit crystallizes cubically in the space group (space group no. 221) with the lattice parameter a = 15.29 Å and one formula unit per unit cell .
See also
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X .
- ↑ Handbook of Mineralogy - Boleite (English, PDF 69.7 kB)
- ↑ a b Boleite at mindat.org (engl.)
literature
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 69 .
- E. Mallard, E. Cumenge: About Boleit, a new mineral . In: Paul Groth (ed.): Journal for crystallography and mineralogy . tape 22 . Leipzig 1894, p. 579 . (available online via archive.org )
Web links
- Mineral Atlas: Boleit (Wiki)