Richterite
The mineral richterite is a relatively rare occurring chain silicate from the group of amphiboles. It crystallizes in the monoclinic crystal system with the chemical composition Na [ CaNa ] (Mg, Fe2 ) 5 [( OH) 2 | Si8O22 ] and usually develops fibrous or acicular to prismatic and perpendicular to the crystallographic a- axis flattened crystals to about 15 cm of yellow, brown, gray violet, dark red to dark green or blue color with white to gray stroke color. In addition to single crystals Richterite often forms single or multiple crystal twins parallel { 100} ( bc plane ) as twins and intergrowth.
Richterite forms with Ferrorichterit a complete solid solution series.
Etymology and history
Was first discovered in Richterite Långban in the Swedish municipality Filipstad and described in 1865 by August Breithaupt ( 1791-1873 ), who named the mineral after Theodor Richter ( 1824-1898 ), to honor his services to the mineral chemistry.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the Richterite belonged to the mineral class of " silicates and Germanates " and then to the Department of " chain silicates and phyllosilicates ( inosilicates ) " where he, along with Aluminobarroisit, alumino- Ferrobarroisit alumino- Magnesiotaramit, Barroisite, Ferribarroisit, ferric Ferrobarroisit, Ferrikatophorit, ferric Magnesiotaramit, Ferritaramit, Ferriwinchit, Ferrobarroisit, Ferrorichterit, Ferro - Winchit, Fluororichterit, potassium fluoro- richterite, Kaliumrichterit, Katophorit, Magnesioferrikatophorit, Magnesiokatophorit, Magnesiotaramit, Parvowinchit, Taramit and Winchit the independent group of " amphibole group, subgroup sodium -calcium amphiboles " was formed.
The 9th edition used since 2001, valid and of the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Richterite also in the class of " silicates and Germanates " and there in the department of " chain silicates and phyllosilicates ( inosilicates ) " a. This division, however, is further subdivided according to the type of chain formation and membership of certain mineral families and the mineral can find accordingly in the subdivision of " Klinoamphibole " back where it along with Aluminobarroisit, alumino- Ferrobarroisit, alumino- Ferrowinchit, Aluminokatophorit, alumino - Magnesiotaramit, Aluminotaramit, Barroisite, Ferribarroisit, ferric Ferrobarroisit, ferric Ferrowinchit, Ferrikatophorit, ferric Magnesiokatophorit, Ferritaramit, Ferriwinchit, Ferrobarroisit, Ferrorichterit, Ferro - Winchit, fluoro - alumino- Magnesiotaramit, fluoro- ferric Magnesiokatophorit, fluoro- Magnesiokatophorit, fluoro -oxy - ferri- magnesiokatophorit, Fluororichterit, Fluorotaramit, potassium Aluminotaramit, potassium fluoro- richterite, Katophorit, magnesiokatophorit, Magnesiotaramit, Parvowinchit, Kaliumferritaramit, Kaliumrichterit, Taramit and Winchit the " Ca -alkali Klinoamphibole, Winchit - richterite - group "with the system no. 9.DE.20 forms.
The classification of minerals according to Dana assigns the richterite in the class of " silicates and Germanates " there, however in the fine already divided the department " chain silicates: Double unbranched chains, W = 2". Here he is with Winchit, Parvowinchit, Ferrowinchit, Ferriwinchit, Ferroferriwinchit, Barroisite, Aluminobarroisit, Ferrobarroisit, Aluminoferrobarroisit, Ferribarroisit, Ferro - Ferribarroisit, ferric Ferrobarroisit, Fluororichterit, potassium Fluororichterit, Kaliumrichterit, Ferrorichterit, Magnesiokatophorit, Katophorit, Magnesioferrikatophorit, Ferrikatophorit, Magnesiotaramit, Aluminotaramit, Aluminomagnesiotaramit, Taramit, ferric 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 subdivision " chain silicates: Double unbranched chains, W = 2 amphibole configuration " to find.
Education and Locations
Richterite formed by contact metamorphism in limestone, alkaline igneous rocks or carbonatites. Also in meteorites Richterite can be found. Accompanying minerals include apatite, calcite, cristobalite, diopside, enstatite, forsterite, leucite, Natrolite, phlogopite, plagioclase, rhodonite and Schefferit.
Worldwide, Richterite so far (as of 2011) are detected at around 100 localities. We are especially famous of the places where Wilberforce in Canada and Långban in Sweden because of there occurring, large Richteritkristalle of up to 20 cm in length.
Except at its type locality Långban in Värmland in Sweden yet there is Richterite at Garpenberg in the community Hedemora, Ultevis in Lapland, on Alnön and Söråker in Medelpad and in Hällefors, Lindenberg and Norberg in Västmanland.
In Austria, the mineral previously occurred only in Drossendorf - Zissersdorf on the Waldviertel / Lower Austria and Switzerland it has so far been found only in Maloja in the canton of Grisons.
Other localities are the regions of Badakhshan in Afghanistan; Victoria and Western Australia in Australia; São Paulo, Brazil; the Balkan Mountains in Bulgaria; Inner Mongolia in China; Corsica in France; Madhya Pradesh and West Bengal in India; Valle d'Aosta, Lazio, Liguria and Piedmont in Italy; Honshu in Japan; British Columbia, Ontario and Quebec in Canada; Nyanza in Kenya; Fianarantsoa in Madagascar; of Kachin State in Myanmar; Otjozondjupa in Namibia; the North Island in New Zealand; Lower Silesia in Poland; Eastern Siberia, and the Kola 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 U.S. states of Arizona, Arkansas, California, Colorado, Hawaii, Kansas, Montana, New Jersey, Texas, Utah and Wyoming.
Crystal structure
Richterite crystallized in the monoclinic space group (space group No. 12) with lattice parameters a = 9.90 Å, b = 17.98 Å, c = 5.27 Å and β = 104.2 ° and two formula units per unit cell.