Serrabrancaite
| Serrabrancaite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1998-006 |
| chemical formula | Mn [PO 4 ] • H 2 O |
|
Mineral class (and possibly department) |
Phosphates, arsenates, vanadates |
|
System no. to Strunz and to Dana |
8.CB.05 ( 8th edition : VII / C.07) 04/40/10/01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic 2 / m |
| Space group | C 2 / c |
| Lattice parameters |
a = 6.91 Å ; b = 7.47 Å; c = 7.36 Å β = 112.3 ° |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 3.5 |
| Density (g / cm 3 ) | measured: 3.17; calculated: 3.16 |
| Cleavage | no |
| Break ; Tenacity | uneven, brittle |
| colour | dark brown, greenish black |
| Line color | olive green |
| transparency | translucent |
| shine | Diamond luster |
| Crystal optics | |
| Refractive indices |
n α = 1.750 n β = 1.790 n γ = 1.800 |
| Birefringence | δ = 0.050 |
Serrabrancait is a very rare mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the monoclinic crystal system with the chemical composition Mn [PO 4 ] • H 2 O and develops only small, isometric crystals up to about 0.3 mm in size from dark brown to greenish-black color and olive-green line color .
Etymology and history
Serrabrancaite was first found in 1998 in the pegmatites of Serra Branca in the Brazilian state of Paraíba and described by Thomas Witzke , Reinhard Wegner, Thomas Doering, Herbert Pöllmann and Walter Schuckmann († 1998), who named the mineral after its type locality . Serrabrancaite was recognized as an independent mineral by the International Mineralogical Association (IMA) in the same year under the number IMA1998-006 . The test results and the recognized name were published two years later in American Mineralogist , Volume 85 (2000).
classification
In the old (8th edition) and new systematics of minerals according to Strunz (9th edition) , the serrabrancaite belongs to the division of "water-containing phosphates without foreign anions ".
Since the revision of Strunz's mineral systematics in the 9th edition in 2001, this section has been subdivided more precisely according to the size of the cations involved in the compound and the molar ratio of phosphate, arsenate or vanadate complex to crystal water . The serrabrancaite can be found accordingly in the new subdivision "With only medium-sized cations, RO 4 : H 2 O = 1: 1", where it is the only member of the unnamed group 8.CB.05 .
The systematics of minerals according to Dana , which is common in the English-speaking world , also assigns the serrabrancaite to the class of "phosphates, arsenates and vanadates", but there in the department of "hydrated phosphates etc. with the general formula A 3+ XO 4 • x (H 2 O) ", where he is the only member of the" Phosphate analogues of the kieserite (SO4) group (C2 / c) "with the system no. 40.04.10 forms.
Education and Locations
Serrabrancaite is a secondary mineral and forms as a weathering product from triplite in phosphate- containing pegmatites . Accompanying minerals include vernadite and phosphosiderite .
Worldwide, Serrabrancaite has so far (status: 2010) apart from its type locality Serra Branca only in the pegmatite of Buranga ( Gatumba district ) in the western province of Rwanda .
Crystal structure
Serrabrancaite crystallizes monoclinically in the space group C 2 / c with the lattice parameters a = 6.91 Å ; b = 7.47 Å; c = 7.36 Å and β = 112.3 ° as well as 4 formula units per unit cell .
See also
Web links
literature
- Thomas Witzke, Reinhard Wegner, Thomas Doering, Herbert Pöllmann, Walter Schuckmann: Serrabrancaite, MnPO 4 H 2 O, a new mineral from the Alto Serra Branca pegmatite, Pedra Lavrada, Paraiba, Brazil . In: American Mineralogist . tape 85 , 2000, pp. 847-849 ( PDF ).
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. 474 .
- ↑ Webmineral - Serrabrancaite (English)
- ↑ a b c Serrabrancaite at mindat.org (engl.)