Triploidite
| Triploidite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Mn 2+ 2 [OH |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.BB.15 ( 8th edition : VII / B.03) 06/41/03/02 |
| Similar minerals | Wolfeit |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | P 2 1 / a (No. 14, position 3) |
| Lattice parameters |
a = 12.37 Å ; b = 13.23 Å; c = 9.84 Å β = 108.4 ° |
| Formula units | Z = 16 |
| Physical Properties | |
| Mohs hardness | 4.5 to 5 |
| Density (g / cm 3 ) | measured: 3.70; calculated: [3.80] |
| Cleavage | good after {100}, clear after {120}, indistinct after {010} |
| Break ; Tenacity | uneven to slightly scalloped |
| colour | brownish-pink, wine-yellow to yellowish-brown, red-orange |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss, diamond gloss, fat gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.709 to 1.735 n β = 1.710 to 1.736 n γ = 1.714 to 1.740 |
| Birefringence | δ = 0.005 |
| Optical character | biaxial positive |
Triploidite is a rarely occurring mineral from the mineral class of "phosphates, arsenates and vanadates". It crystallizes in the monoclinic crystal system with the idealized chemical composition Mn 2+ 2 [OH | PO 4 ] and is therefore chemically seen a manganese - phosphate with additional hydroxide .
Since triploidite with Wolfeit (Fe 2+ 2 [OH | PO 4 ]) forms a gapless mixed crystal row, part of the manganese can be represented ( substituted ) by iron , which is indicated in various sources with the formula (Mn, Fe) 2 [OH | PO 4 ] is expressed.
Triploidit develops prismatic to columnar, parallel to the c-axis stretched and striped crystals up to about one millimeter in length with a glass, diamond or fat-like shine on the surfaces. Often it is also found in the form of parallel- fiber or spherulitic (spherical) mineral aggregates and irregular grains. Depending on the mixing ratio of manganese and iron or foreign admixtures of other elements , the transparent to translucent crystals are brownish-pink, wine-yellow to yellowish-brown or orange-red in color. The line color of the mineral, on the other hand, is always white.
Etymology and history
Triploidite was first discovered in the "Abija N. Fillow" quarry (also Branchville quarry ) near Branchville in Fairfield County , Connecticut . The mineral was described in 1878 by George Jarvis Brush and Edward Salisbury Dana , who alluded to its similarity in habit and chemical composition to the related mineral triplite and the ancient Greek εἶδος eidos for what can be seen or the shape , more precisely the Greek perfect form οἶδα [oida] for I've seen named.
The type material of the mineral is stored at Yale University in New Haven (catalog numbers 5.5646 to 5.5648).
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the triploidite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "anhydrous phosphates, with foreign anions F, Cl, O, OH", where together with Hydroxylwagnerit (IMA 2004-009), Joosteit , Magniotriplit (discredited 2004), Sarkinit , Staněkit , Triplit , Wagnerit , Wolfeit and Zwieselit the "Zwieselit-Wolfeit-Gruppe" with the system no. VII / B.03 formed.
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 triploidite to the category of “phosphates etc. with additional anions; without H 2 O “. However, this is further subdivided according to the relative size of the cations involved and the molar ratio of the additional anions to the phosphate, arsenate and vanadate complex, so that the mineral is classified in the sub-section “With only medium-sized cations; (OH etc.): RO 4 ≤ 1: 1 “can be found where the name is now given by the“ triploidite group ”with the system no. 8.BB.15 and the other members Joosteit, Sarkinit, Staněkit , Wagnerit and Wolfeit.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns triploidite to the class of "phosphates, arsenates and vanadates" and there to the category of "anhydrous phosphates, etc., with hydroxyl or halogen". Here, however, he is in the " Wolfeit group " with the system no. 41.06.03 within the subsection "Anhydrous phosphates etc., with hydroxyl or halogen with (A) 2 (XO 4 ) Z q ".
Crystal structure
Triploidite crystallizes monoclinically in the space group P 2 1 / a (space group no. 14, position 3) with the lattice parameters a = 12.37 Å ; b = 13.23 Å; c = 9.84 Å and β = 108.4 ° and 16 formula units per unit cell .
Education and Locations
Triploidite forms hydrothermally as a conversion product from primary phosphates in granitic pegmatites . The accompanying minerals include dickinsonite , eosphorite , lithiophilite , rhodochrosite , triphyline and triplite .
As a rare mineral formation, triploidite could only be detected in a few localities, whereby so far (as of 2015) around 30 localities are known. Its type locality quarry "Abija N. Fillow" near Branchville is the only known site in Connecticut to date. Other triploidite finds in the United States are known from Yavapai County in Arizona; the Oxford County in Maine; Grafton and Rockingham Counties in New Hampshire, Cleveland Counties in North Carolina, and Custer and Pennington Counties in South Dakota.
In Germany, the mineral has so far only been found in one passage - outcrop at Trutzhofmühle (municipality of Pleystein ) and in a silver mine near Waidhaus in the Upper Palatinate district of Neustadt an der Waldnaab (Bavaria).
Other previously known sites in Europe include Wheal Owles near Botallack in the English county of Cornwall , Hunnakko (rural municipality Kuortane ) near the city of Alavus in western Finland, Skrumpetorp near Godegård in the Swedish province of Östergötland and Přibyslavice in Okres Kutná Hora and St Vavřinec Hill near Domažlice in the Czech region of Bohemia .
Otherwise, triploidite could still be found at some sites in South Australia , in the Brazilian state of Rio Grande do Norte , the Canadian provinces of Manitoba , Nova Scotia and the Northwest Territories , in the Guangxi Autonomous Region of the Zhuang in southeast China, the Japanese island of Honshū , in the Eastern Siberia region and in the Far East Federal District in Russia and in the South African province of North Cape .
See also
literature
- Lyneve Waldrop: The crystal structure of triploidite and its relation to the structures of other minerals of the triplite-triploidite group. In: Journal of Crystallography. Volume 131 (1970), pp. 1-20 ( PDF 958 kB )
Web links
- Mineral Atlas: Triploidite (Wiki)
- Web mineral - triploidites
- American-Mineralogist-Crystal-Structure-Database - Triploidite
Individual evidence
- ^ A b c 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. 443 .
- ↑ a b c d e Triploidite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 66.4 kB )
- ↑ a b c d Mindat - Triploidites
- ↑ a b IMA / CNMNC List of Mineral Names; March 2015 (PDF 1.5 MB; p. 178)
- ↑ Mindat - Number of localities for triploidite
- ↑ Find location list for triploidite in the Mineralienatlas and Mindat