Until
Until | |
---|---|
General and classification | |
chemical formula | Bi 2 O 3 |
Mineral class (and possibly department) |
Oxides and hydroxides |
System no. to Strunz and to Dana |
4.CB.60 ( 8th edition : IV / C.02) 03/04/10/02 |
Similar minerals | Sphaerobismoit |
Crystallographic Data | |
Crystal system | monoclinic |
Crystal class ; symbol | monoclinic prismatic (pseudo-orthorhombic) 2 / m |
Space group | P 2 1 / c (No. 14) |
Lattice parameters |
a = 5.8486 Å ; b = 8.1661 Å; c = 7.5097 Å β = 113.00 ° |
Formula units | Z = 4 |
Physical Properties | |
Mohs hardness | 4.5 |
Density (g / cm 3 ) | 8.64 to 9.22 |
Cleavage | is missing |
Break ; Tenacity | uneven |
colour | yellow, green-yellow, gray-green |
Line color | light yellow |
transparency | opaque, transparent to translucent only in very thin layers |
shine | weak diamond luster, matt, earthy |
Crystal optics | |
Refractive index | n = 2.42 |
Birefringence | δ = 0.000 |
Optical character | biaxial |
Bismit (also obsolete bismuth ocher ) is a mineral from the mineral class of oxides and hydroxides . It crystallizes in the monoclinic crystal system with the chemical composition Bi 2 O 3 and usually develops granular to massive mineral aggregates or earthy to powdery coatings in yellow, green-yellow or gray-green color. Crystals are seldom formed and then only microscopic.
It is very soft and easy to grind, opaque and shimmering or matt from yellow to gray to green. It consists of bismuth oxide Bi 2 O 3 with 89.7% bismuth and is contaminated with iron , copper and arsenic .
Etymology and history
Bismit was first described in 1753 by Johan Gottschalk Wallerius , who named the mineral after its composition. The type locality is Wolfgang Maaßen -Grubenfeld (Pucherschacht) near Neustädtel in the Ore Mountains .
classification
In the old (8th edition) and new systematics of minerals according to Strunz (9th edition) , the bismite belongs to the department of "oxides with the molar ratio metal: oxygen = 2: 3", this department in the new Strunz mineral classification The oxides with the molar ratio of metal: oxygen = 3: 5 and similar were expanded and more precisely divided according to the size of the cations . Accordingly, the mineral is now in the “With medium-sized cations” sub-section and forms a separate group there together with Sillénite and Sphaerobismoite .
The systematics of minerals according to Dana also assigns bismite to the class of oxides, but there in the division of "simple oxides with a cation charge of 3+ and the general formula A 2 O 3 ", where it forms a group with claudetite .
Modifications and varieties
The compound Bi 2 O 3 occurs dimorphically in nature and can crystallize in addition to bismite in the tetragonal structure of spherobismoite in space group P 4 2 2 1 2 (space group no. 94) .
Education and Locations
Bismite formed by oxidation of bismuth and, therefore, is usually found as a coating, rough and disseminated in pseudomorphs after Bismuthinit and aikinite .
So far, 156 sites have been registered (as of 2009), including some regions in Australia ; La Paz and Potosí departments in Bolivia; on the Rio Grande in Brazil; Guizhou , Qinghai and Yunnan in China; Baden-Württemberg (Black Forest), Bavaria (Bavarian and Upper Palatinate Forest), Hesse (Odenwald), North Rhine-Westphalia and Rhineland-Palatinate (Siegerland), Saxony-Anhalt (Harz), Saxony (Ore Mountains) and Thuringia (Vogtland) in Germany; Alsace , Auvergne and Brittany in France; Attica in Greece; England in Great Britain; Lombardy , Piedmont and Sardinia in Italy; Honshū and the Nansei Islands in Japan; Ontario in Canada; Kazakhstan ; Kivu in the Democratic Republic of the Congo; Antananarivo and Fianarantsoa in Madagascar; Durango in Mexico; Erongo and Kunene in Namibia; Aust-Agder in Norway; Carinthia and Styria in Austria; Lower Silesia in Poland; Russia (northern and western Siberian regions); Västmanland in Sweden; Canton of Valais in Switzerland; Banská Bystrica and near Košice in Slovakia; Bohemia in the Czech Republic; as well as many regions in the US .
Crystal structure
Bismit crystallizes in the monoclinic crystal system in the space group P 2 1 / c (space group no. 14) with the lattice parameters a = 5.8486 Å ; b = 8.1661 Å, c = 7.5097 Å and β = 113.00 ° as well as four formula units per unit cell .
See also
literature
Clifford Frondel : Mineralogy of the oxides and carbonates of bismuth In: American Mineralogist , Vol. 28, 1943, pp. 521-535 ( PDF )
Web links
- Mineral Atlas: bismite
- Bismit at mindat.org (English)
Individual evidence
- ↑ a b c Webmineral - Bismite (English)
- ↑ a b c American Mineralogist Crystal Structure Database - Bismite (English, 1970)
- ↑ a b Bismite at mindat.org (English)
- ↑ a b Bismite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 66.9 kB )
- ↑ Mindat - Localities for Bismite