Richterite
| Richterite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Na [CaNa] (Mg, Fe 2+ ) 5 [(OH) 2 | Si 8 O 22 ] |
|
Mineral class (and possibly department) |
Silicates and Germanates |
|
System no. to Strunz and to Dana |
9.DE.20 ( 8th edition : VIII / F.09) 66.01.03b.09 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic 2 / m |
| Space group | C 2 / m |
| Lattice parameters |
a = 9.90 Å ; b = 17.98 Å; c = 5.27 Å β = 104.2 ° |
| Formula units | Z = 2 |
| Twinning | simple and multiple twins in parallel {100} |
| Physical Properties | |
| Mohs hardness | 5 to 6 |
| Density (g / cm 3 ) | measured: 2.97 to 3.45; calculated: [3.10] |
| Cleavage | completely after {110}, gap angle ~ 56 ° and ~ 124 °; Secretions according to {100} and {001} |
| Break ; Tenacity | uneven, brittle |
| colour | yellow, brown, gray-violet, dark red, dark green, blue |
| Line color | white to gray |
| transparency | transparent to translucent |
| shine | Glass gloss, matt |
| Crystal optics | |
| Refractive indices |
n α = 1.615 n β = 1.629 n γ = 1.636 |
| Birefringence | δ = 0.021 |
| Optical character | biaxial negative |
| Axis angle | 2V = measured: 68 °; calculated: 70 ° |
| Pleochroism | strong: light yellow, orange, red |
The mineral Richterite is a relatively rare chain silicate from the amphibole group . It crystallizes in the monoclinic crystal system with the chemical composition Na [CaNa] (Mg, Fe 2+ ) 5 [(OH) 2 | Si 8 O 22 ] and develops mostly fibrous or needle-like to prismatic and perpendicular to the crystallographic a -axis [100] Flattened crystals up to about 15 cm in size from yellow, brown, gray-violet, dark red to dark green or blue in color with white to gray streak color . In addition to single crystals , Richterite often forms simple or multiple crystal twins parallel {100} ( bc -plane) as twin and intergrowth planes.
Richterite forms a complete mixed crystal row with ferro-straighterite .
Etymology and history
Richterite was first discovered in Långban in the Swedish municipality of Filipstad and described in 1865 by August Breithaupt (1791–1873), who named the mineral after Theodor Richter (1824–1898) in honor of his services to mineral chemistry.
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the Richterite belonged to the mineral class of "silicates and germanates" and there to the department of "chain silicates and band silicates (inosilicates)", where together with aluminobarroisite , alumino-ferrobarroisite , alumino-Magnesiotaramite , Barroisit , Ferribarroisit , ferric Ferrobarroisit , Ferrikatophorit , ferric Magnesiotaramite , Ferritaramit , Ferriwinchit , Ferrobarroisit , Ferrorichterit , Ferro-winchite , Fluororichterit , potassium-fluoro-richterite , Kaliumrichterit , Katophorit , Magnesioferrikatophorit , Magnesiokatophorite , Magnesiotaramite , Parvowinchit , Taramit and Winchit formed the independent group of the " amphibole group , subgroup sodium-calcium amphiboles ".
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 Richterite to the class of "silicates and germanates" and there in the department of "chain silicates and band silicates (inosilicates)" . This section is, however, further subdivided according to the type of chain formation or membership in certain mineral families and the mineral can be found accordingly in the subdivision of “Chain and band silicates with 2-periodic double chains, Si 4 O 11 ; Amphibole family, Klinoamphibole "back where it along with Aluminobarroisit, alumino-Ferrobarroisit, alumino-Ferrowinchit , Aluminokatophorit , alumino-Magnesiotaramite, Aluminotaramit , Barroisit, Ferribarroisit, ferric Ferrobarroisit, ferric Ferrowinchit , Ferrikatophorit , ferric Magnesiokatophorite, Ferritaramit Ferriwinchit, Ferrobarroisit, Ferrorichterit, Ferro-winchite, fluoro-alumino-Magnesiotaramite , fluoro ferric Magnesiokatophorite , fluoro Magnesiokatophorite , fluoro-oxy-ferri-Magnesiokatophorite , Fluororichterit, Fluorotaramit , potassium Aluminotaramit , potassium-fluoro-richterite, Katophorit, Magnesiokatophorit, Magnesiotaramit, Parvowinchit, Kaliumferritaramit, Kaliumrichterit, Taramit and Winchit the "Ca-Alkali-Klinoamphibole, Winchit-Richterit-Gruppe" with the system no. 9.DE.20 forms.
The systematics of minerals according to Dana also assigns Richterite to the class of "silicates and germanates", but there in the more finely subdivided division of "chain silicates: double unbranched chains, W = 2". Here it is together with Winchit, Parvowinchit, Ferrowinchit, Ferriwinchit, Ferroferriwinchit, Barroisit, Aluminobarroisit, Ferrobarroisit, Aluminoferrobarroisit, Ferribarroisit, Ferro-Ferrobarroisit, Ferri-Ferrobarroisit, Ferri-Ferrobarroisit, Magoforo-Horopit, Magoforo-Horophoricite, Potassium-Fluorophoricite, Potassium-Horophoricite , Magnesiotaramit, Aluminotaramit, Aluminomagnesiotaramit, Taramit, Ferri-Magnesiotaramit, Ferritaramit, Fluoropargasit, Parvo-Mangano-Edenit and Parvo-Manganotremolit in the "Group 3, Sodium-Calcium-Amphibole" with the system no. 66.01.03b within the subsection “ Chain Silicates: Double unbranched chains, W = 2 amphibole configuration ”.
Education and Locations
Richterite is formed by contact metamorphosis in limestone , alkaline igneous rocks or carbonatites . Richterite can also be found in meteorites . Accompanying minerals include apatite , calcite , cristobalite , diopside , enstatite , forsterite , leucite , natrolite , phlogopite , plagioclase , rhodonite and schefferite .
So far (as of 2011) Richterite has been found at around 100 sites worldwide. The sites Wilberforce in Canada and Långban in Sweden are particularly well-known because of the large Richterite crystals up to 20 cm in length that occur there.
In addition to its type locality Långban in Värmland , Richterit can also be found in Sweden near Garpenberg in the municipality of Hedemora , Ultevis in Lapland , on Alnön and near Söråker in Medelpad and near Hällefors , Lindesberg and Norberg in Västmanland .
In Austria, the mineral has so far only occurred near Drosendorf-Zissersdorf in the Waldviertel / Lower Austria and in Switzerland it has so far only been found near Maloja in the canton of Graubünden.
Other locations are the Badakhshan regions in Afghanistan; Victoria and Western Australia in Australia; São Paulo in Brazil; the Balkan Mountains in Bulgaria; the Inner Mongolia in China; Corsica in France; Madhya Pradesh and West Bengal in India; the Aosta Valley , Latium , Liguria and Piedmont in Italy; Honshū in Japan; British Columbia , Ontario and Quebec in Canada; Nyanza in Kenya; Fianarantsoa in Madagascar; the Kachin State in Myanmar; Otjozondjupa in Namibia; the North Island in New Zealand; Lower Silesia in Poland; Eastern Siberia , Kola and the Urals in Russia; the Okres Prešov in Slovakia; the Canary Islands , Castile-La Mancha and Murcia in Spain; the Kalahari in South Africa; Tororo in Uganda and in the US states of Arizona , Arkansas , California , Colorado , Hawaii , Kansas , Montana , New Jersey , Texas , Utah and Wyoming .
Crystal structure
Richterite crystallizes monoclinically in the space group (space group No. 12) with the lattice parameters a = 9.90 Å , b = 17.98 Å, c = 5.27 Å and β = 104.2 ° as well as two formula units 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 , p. 630 .
- ↑ a b c d e f Handbook of Mineralogy - Richterite (English, PDF 78 kB)
- ↑ Webmineral - Richterite (English)
- ↑ a b c d Richterite at mindat.org (engl.)
literature
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 240 .
