Népouite

• Garnierite

• (Ni, Mg) 6 [( OH) 8 | Si4O10 ]

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 Ni3 [( OH) 4 | Si2O5 ], that is chemically a basic nickel silicate. Structurally Népouit one of the phyllosilicates.

Népouit is the nickel analogue of lizardite ( Mg3 [( OH) 4 | Si2O5 ] ) and forms a complete solid solution series. In natural Népouit therefore is usually a small portion of nickel is replaced by magnesium ( substituted ), which is expressed in the formula set out in parentheses element symbols: (Ni, Mg) 6 [( OH) 8 | Si4O10 ]

The mineral is translucent and develops rarely rough, pseudo-hexagonal, worm -like crystals. He usually can be found in the form of coarse, nieriger, stalaktitischer or peel-like mineral aggregate from dark green to dull green color, which is sometimes described as emerald green.

Etymology and history

Was first discovered in the Népouit " Népoui Mine", a mine on the Népoui Peninsula in the New Caledonian community Poya in which the népouithaltige among other garnierite nickel ore is mined. Was first described in 1907 by E. Mineral Glasser, who named it after its type locality.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Népouit belonged to the department of " layer silicates ( phyllosilicates ) ," where he, along with amesite, antigorite, berthierine, Brindleyit, Carlosturanit, chrysotile, Cronstedtit, Dozyit, fraipontite Greenalith, Karpinskit, Karyopilith, Kellyit, lizardite and Pecorait the " serpentine " with the system no. VIII/H.27 formed.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Népouit also in the department of " layer silicates ( phyllosilicates ) " a. However, this is further subdivided according to the crystal structure, so that the mineral according to its construction in the subsection " layer silicates ( phyllosilicates ) with kaolinite layers composed of tetrahedral or octahedral networks " is to find where it also together with amesite, antigorite, berthierine, Brindleyit, chrysotile, Cronstedtit, fraipontite, Greenalith, Karyopilith, Kellyit, lizardite, and Manandonit Pecorait the " serpentine " with the system no. 9.ED.15 forms.

The mainly common in English-speaking classification of minerals according to Dana assigns the Népouit in the department of " layer silicate minerals " one. Here he is with Karyopilith, lizardite and Greenalith in the " serpentine ( lizardite - subgroup ) " with the system no. ": With 1-1 layers of layers of six-membered rings phyllosilicates " to find 71.01.02b within the subdivision.

Modifications and varieties

The compound Ni3 [( OH) 4 | Si2O5 ] is dimorphic and is found in nature in addition to the orthorhombic crystallized as monoclinic Népouit still crystallizing Pecorait ago.

Education and Locations

Népouit formed by metamorphism in nickel-rich ultramafic rocks. Accompanying minerals occur among others in various serpentine, chlorite, hydrous nickel silicates and iron oxides.

A rare mineral formation Népouit could be detected only in a few localities, where so far (as of 2013) are considered to be known about 50 localities. Apart from its type locality " Népoui Mine" the mineral still came to light on New Caledonia in several places in the northern and southern province.

In Germany they found Népouit in the quarry Zeilberg in Bavaria and in the nickel mine Callnberg North (No. 2) in Saxony.

The only known locality in Austria is the town of Gmünd in Kärnten.

Other localities lie including Australia, the Dominican Republic, Greece, the Democratic Republic of Congo ( Zaire ), Indonesia, Italy, Japan, Morocco, Poland, Portugal, Russia, South Africa, Czech Republic and in several states of the USA.

Crystal structure

Népouit crystallizes in the orthorhombic space group Ccm21 ( Raumgruppen-Nr. 36) with the lattice parameters a = 5.31 Å; b = 9.19 Å and c = 14.50 Å and two formula units per unit cell.

Use

Népouit is an important raw material for the production of nickel.