Yanomamit
| Yanomamit | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1990-052 |
| chemical formula | In [AsO 4 ] • 2H 2 O |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8th CD.10 ( 8th edition : VII / C.09) 04/40/01/05 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic-dipyramidal; 2 / m 2 / m 2 / m |
| Space group | Pcab (No. 61, position 2) |
| Lattice parameters | a = 10.47 Å ; b = 10.34 Å; c = 9.09 Å |
| Formula units | Z = 8 |
| Physical Properties | |
| Mohs hardness | 3.5 to 4 ( VHN 25 = 571 to 743) |
| Density (g / cm 3 ) | calculated: 3.876 (3) |
| Cleavage | Please complete |
| colour | yellow, yellowish green, light green |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive index | n = 1.65 |
| Optical character | biaxial positive |
| Axis angle | 2V = 55 to 76 ° |
| Other properties | |
| Chemical behavior | Easily soluble in 35% hydrochloric acid , soluble in 95% sulfuric acid |
Yanomamit is a very rare occurring mineral from the mineral class of "phosphates, arsenates and vanadates" with the chemical composition in [AsO 4 ] • 2H 2 O, making it chemically seen a hydrous indium - arsenate .
Yanomamite crystallizes in the orthorhombic crystal system and develops idiomorphic, dipyramidal crystals with a glass-like sheen on the surfaces. However, it is mostly found in the form of crusty coatings or is itself epitaxially overgrown with scorodite (Fe 3+ [AsO 4 ] · 2H 2 O). In its pure form, yanomaite is colorless and transparent. However, due to foreign admixtures , it usually takes on a yellow, yellowish green or light green color, whereby the transparency decreases accordingly.
Etymology and history
Yanoma was first discovered in 1990 in the tin- indium deposit "Mangabeira" on Monte Alegre de Goiás in the Brazilian state of Goiás and described in 1994 by Nilson F. Botelho, Guy Roger, Ferdinand d'Yvoire, Yves Moëlo, Marcel Volfinger. They named the mineral after the Yanomami Indians living in the Amazon basin , where the find area is located.
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the yanomaite belonged to the class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates without foreign anions ", where together with Kolbeckite , Koninckit , Malhmoodite , mansfieldite , metavariscite , paraskorodite , phosphosiderite , scorodite , strictite and variscite the "variscite group" with the system no. VII / C.09 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 Yanomamite to the category of “phosphates etc. without additional anions; with H 2 O “. However, this is further subdivided according to the relative size of the cations involved and the molar ratio of the phosphate, arsenate or vanadate complex (RO 4 ) to the water of crystallization content , so that the mineral can be classified according to its composition in the subsection “With only medium-sized cations; RO 4 : H 2 O = 1: 2 ”is to be found, where together with Mansfieldite, Redondite , Skorodite, Strengite and Variscite the“ Variscite group ”with the system no. 8.CD.10 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Yanomamite to the class of "phosphates, arsenates and vanadates" and there in the department of "water-containing phosphates etc.". Here it is also together with Mansfieldite, Skorodite, Strengite and Variscite in the " Variscite group " with the system no. 40.04.01 to be found in the sub-section "Water-containing phosphates etc., with A 3+ XO 4 × x (H 2 O)".
Crystal structure
Yanomamite crystallizes isotypically with scorodite in the orthorhombic crystal system in the space group Pcab (space group no. 61, position 2) with the lattice parameters a = 10.47 Å ; b = 10.34 Å and c = 9.09 Å and 8 formula units per unit cell .
Education and Locations
As a rare secondary mineral, yanomamite is formed by weathering or displacement of arsenopyrite and sphalerite, which is rich in indium .
At its type locality , the Mangabeira tin deposit about 350 km north of Brasília in the southern part of the Amazon basin, the mineral was found in veins of quartz - topaz - greisen in pink, porphyry biotite - granite . In addition to scorodite, arsenopyrite and sphalerite, cassiterite appeared as accompanying minerals .
The only other known site (as of 2016) is the Aveleiras Mine in the municipality of Mire de Tibães in northern Portugal.
See also
literature
- Nilson F. Botelho, Guy Roger, Ferdinand d'Yvoire, Yves Moëlo, Marcel Volfinger: Yanomamite, InAsO 4 · 2H 2 O, a new indium mineral from topaz-bearing greisen in the Goiás Tin Province, Brazil. In: European Journal of Mineralogy. Volume 6 (1994), pp. 245-254 ( PDF 880.7 kB )
Web links
- Mineral Atlas: Yanomamite (Wiki)
- Mindat - Yanomamite
- Web mineral - Yanomamite
- Database-of-Raman-spectroscopy - Yanomamite
Individual evidence
- ↑ a b c d e f 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. 478 .
- ↑ a b Yanomamite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 65.3 kB )
- ↑ Nilson F. Botelho, Guy Roger, Ferdinand d'Yvoire, Yves Moëlo, Marcel Volfinger: Yanomamite, InAsO 4 2H 2 O, a new indium mineral from topaz-bearing greisen in the Goiás Tin Province, Brazil. In: European Journal of Mineralogy. Volume 6 (1994), p. 248 ( PDF 880.7 kB ; p. 4)
- ↑ Find location list for Yanomamit in the Mineralienatlas and Mindat