Népouit
| Népouit | |
|---|---|
 |
|
| General and classification | |
| other names |
Garnierite |
| chemical formula | Ni 3 [(OH) 4 | Si 2 O 5 ]
|
|
Mineral class (and possibly department) |
Silicates, Germanates - layered silicates (phyllosilicates) |
|
System no. to Strunz and to Dana |
9.ED.15 ( 8th edition : VIII / H.27) 71.01.02b.03 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic-pyramidal; mm 2 |
| Room group (no.) | Ccm 2 1 (No. 36) |
| Lattice parameters | a = 5.31 Å ; b = 9.19 Å; c = 14.50 Å |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 2.5 |
| Density (g / cm 3 ) | measured: 3.24; calculated: [3.07 to 3.40] |
| Cleavage | good according to [001] and [010] |
| Break ; Tenacity | shell-like, sharp-edged |
| colour | dark green to pale green, emerald green |
| Line color | light green |
| transparency | translucent |
| shine | Glass gloss, pearlescent |
| Crystal optics | |
| Refractive indices |
n α = 1.622 n β = 1.579 to 1.645 n γ = 1.645 |
| Birefringence | δ = 0.035 |
| Optical character | biaxial negative |
| Pleochroism | weak: x = dark green, z = yellow green |
Népouit (formerly garnierite ) is a rarely occurring mineral from the mineral class of " silicates and germanates ". It crystallizes in the orthorhombic crystal system with the idealized chemical composition Ni 3 [(OH) 4 | Si 2 O 5 ], so it is chemically a basic nickel silicate. Structurally, Népouit belongs to the layered silicates .
Népouit is the nickel analogue of lizardite (Mg 3 [(OH) 4 | Si 2 O 5 ]) and forms a complete mixed crystal row with it . In natural Népouit, therefore, a small amount of nickel is usually replaced ( substituted ) by magnesium , which is expressed in the formula with element symbols in round brackets: (Ni, Mg) 6 [(OH) 8 | Si 4 O 10 ]
The mineral is translucent and rarely develops coarse, pseudo-hexagonal, worm-shaped crystals . It is usually found in the form of coarse, kidney-shaped, stalactitic or peeled mineral aggregate of dark green to dull green color, which is sometimes also described as emerald green.
Etymology and history
Népouit was first discovered in the "Népoui Mine", a mine on the Népoui peninsula in the New Caledonian municipality of Poya , where the nickel ore garnierite , which contains népouit , is mined. The mineral 1907 E. Glasser, it was first described by its type locality named.
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the Népouit belonged to the department of "phyllosilicates (phyllosilicates)", where together with Amesite , Antigorite , Berthierin , Brindleyite , Carlosturanite , Chrysotile , Cronstedtite , Dozyite , Fraipontite , Greenalith , Karpinskit , Karyopilith , Kellyit , Lizardit and Pecorait the " serpentine group " with the system no. VIII / H.27 .
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 classifies the Népouit in the “phyllosilicates” department. This is, however, further subdivided according to the crystal structure , so that the mineral can be found according to its structure in the sub-section "Layered silicates (phyllosilicates) with kaolinite layers, composed of tetrahedral or octahedral networks", where it can also be found together with Amesite, Antigorite, Berthierin, Brindleyite , Chrysotile, cronstedtite, fripontite, greenalite, karyopilite, kellyite, lizardite, manandonite and pecoraite the "serpentine group" with the system no. 9.ED.15 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking area , also classifies the Népouit in the “layered silicate minerals” department. Here it is together with karyopilith, lizardite and greenalith in the " serpentine group (lizardite subgroup) " with the system no. 71.01.02b can be found in the subsection "Layered Silicates: Layers of six-membered rings with 1: 1 layers".
Modifications and varieties
The compound Ni 3 [(OH) 4 | Si 2 O 5 ] is dimorphic and occurs in nature in addition to the orthorhombic crystallizing népouite as a monoclinic crystallizing pecoraite .
Education and Locations
Népouit is formed by metamorphosis in nickel-rich, ultramafic rocks . Various serpentines , chlorites , hydrous nickel silicates and iron oxides occur as accompanying minerals .
As a rare mineral formation, Népouit could only be proven at a few sites, whereby so far (as of 2013) around 50 sites are known. In addition to its type locality “Népoui Mine”, the mineral appeared on New Caledonia in several places in the northern and southern provinces .
In Germany, Népouit was found in the Zeilberg quarry in Bavaria and in the Callenberg Nord nickel mine (No. 2) in Saxony.
The only known site in Austria so far is the community of Gmünd in Carinthia .
Other sites are found in Australia, the Dominican Republic, Greece, the Democratic Republic of the Congo (Zaire), Indonesia, Italy, Japan, Morocco, Poland, Portugal, Russia, South Africa, the Czech Republic and in several states in the USA.
Crystal structure
Népouit crystallizes orthorhombically in the space group Ccm 2 1 (space group no. 36) with the lattice parameters a = 5.31 Å ; b = 9.19 Å and c = 14.50 Å and 2 formula units per unit cell .
use
Népouit is an important raw material for the extraction of nickel .
See also
literature
- Helmut Schrätze, Karl-Ludwig Weiner: Mineralogy. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 846 (as garnierite ) .
Web links
Individual evidence
- ↑ a b c IMA / CNMNC List of Mineral Names - Népouite (PDF 1.3 MB; February 2013)
- ↑ 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. 677 .
- ↑ Webmineral - Népouite
- ↑ a b c d e f Népouite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 60.8 kB )
- ↑ Stefan Weiß: The large Lapis mineral directory . 4th edition. Christian Weise Verlag, Munich 2002, ISBN 3-921656-17-6
- ↑ Mindat - Népouite
- ↑ Martin Okrusch, Siegfried Matthes: Mineralogie. An introduction to special mineralogy, petrology and geology . 7th fully revised and updated edition. Springer Verlag, Berlin et al. 2005, ISBN 3-540-23812-3 .
- ↑ Mindat - Number of localities for Népouite
- ↑ Find location list for Népouit in the Mineralienatlas and in Mindat