Chapmanite
| Chapmanite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | SbFe 3+ 2 [OH | Si 2 O 8 ] |
|
Mineral class (and possibly department) |
Silicates and Germanates |
|
System no. to Strunz and to Dana |
9.ED.20 ( 8th edition : VIII / B.06) 71.01.03.02 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic; m |
| Space group | Cm (No. 8) |
| Lattice parameters |
a = 5.19 Å ; b = 8.99 Å; c = 7.70 Å β = 100 ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 2.5 |
| Density (g / cm 3 ) | measured: 3.69 to 3.75; calculated: 4.29 |
| Cleavage | no |
| Break ; Tenacity | shell-like to irregular |
| colour | green-yellow, yellow, olive-green |
| Line color | greenish yellow |
| transparency | translucent |
| shine | earthy matt, diamond shine |
| Crystal optics | |
| Refractive indices |
n α = 1.850 n β = 1.950 n γ = 1.960 |
| Birefringence | δ = 0.110 |
| Optical character | biaxial negative |
| Axis angle | 2V = calculated: 32 ° |
Chapmanite ( Höferite ) is a rare mineral from the mineral class of " silicates and germanates ". It crystallizes in the monoclinic crystal system with the chemical composition SbFe 3+ 2 [OH | Si 2 O 8 ] and develops predominantly earthy and massive mineral aggregates , rarely also strip-shaped, tabular to prismatic crystals of yellow, yellowish-green or green color with yellow-green Line color .
Etymology and history
Chapmanite was first discovered in the "Keeley Frontier Mine" near South Lorrain (Cobalt Gowganda Region) in the Timiskaming District (Ontario, Canada) and described in 1924 by Thomas Leonard Walker (1867–1942), who named the mineral after the English Canadian mineralogist Edward John Chapman (1821-1904) named.
classification
In the now outdated, but still common 8th edition of the mineral classification according to Strunz , the chapmanite belonged to the mineral class of "silicates and germanates" and there to the department of " island silicates with non-tetrahedral anions (Neso subsilicates)", where together with bismuth ferrit it was an independent one Group formed.
The valid since 2001 and by the International Mineralogical Association used (IMA) 9th edition of Strunz'schen systematic mineral also assigns the chapmanite in the class of "silicates and Germanates" and then in the Department of " phyllosilicates one (phyllosilicates)". This department is, however, further subdivided according to the type of layer formation, so that the mineral, according to its structure, can be found in the sub-department "Layered silicates (phyllosilicates) with kaolinite layers, composed of tetrahedral or octahedral networks", where it is named after the "Chapmanite Group" with the system no. 9.ED.20 and the other members allophane , bismuth ferrite, chrysocolla , imogolite and neotokite .
The systematics of minerals according to Dana also assigns the chapmanite to the class of "silicates and germanates" and there in the department of "layered silicate minerals". Here it is together with bismuth ferrite in the "bismuth ferrite group" with system no. 71.01.02d can be found in the subsection “ Layered Silicates: Layers of six-membered rings with 1: 1 layers ”.
Crystal structure
Chapmanite crystallizes in the monoclinic space group Cm (space group no. 8) with the lattice parameters a = 5.19 Å , b = 8.99 Å, c = 7.70 Å and β = 100 ° as well as 2 formula units per unit cell .
Education and Locations
Chapmanite formed secondarily in gneisses that of hydrothermal - veins were penetrated. Accompanying minerals include silver and stibnite .
So far (as of 2011) Chapmanite has been found at around 20 sites worldwide. In addition to its type locality “Keeley-Frontier Mine”, the mineral was also found in Canada in the “Nipissing 404 Mine”, also located in the Timiskaming District . are u. a. Bräunsdorf and Freiberg in Saxony, Smilkov (Czech Republic) and the Keeley silver mine in Ontario (Canada).
In Germany, chapmanite has so far only been found in the New Hope God's treasure trove near Bräunsdorf (Oberschöna) in the Saxon Ore Mountains.
Other locations include Bohemia in the Czech Republic; Auvergne , Alsace and Lorraine in France; the Tuscany in Italy; Kyushu in Japan; the Alai Mountains in Kyrgyzstan; Bratislava in Slovakia; Asturias in Spain and Nevada in the USA.
See also
literature
- Strübel G. & Zimmer SH (2001): Lexicon of Minerals. Enke publishing house, Stuttgart
- Chapmanite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 72.5 kB )
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 205 .
Web links
- Mineral Atlas: Chapmanite (Wiki)
- RRUFF Database-of-Raman-spectroscopy - Chapmanite
- American-Mineralogist-Crystal-Structure-Database - Chapmanite
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 , p. 679 .
- ↑ Webmineral - Chapmanite (English)
- ↑ a b c d e f Mindat - Chapmanite (English)
- ↑ Journal Mineralogical Society of America - New Minerals: New Species (PDF 189.5 kB; Chapmanite: p. 3)
- ↑ Mineralogical Records - Walker, Thomas Leonard ( Memento of the original from October 6, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (English)
