Népouite
Encyclopedia
Népouite is a rare nickel
silicate mineral which has the apple green colour typical of such compounds. It was named by E Glasser in 1907 after the place where it was first described (the type locality
), the Népoui Mine, Népoui, Nouméa Commune, Northern Province, New Caledonia
. The ideal formula is Ni
(Si
O
)(OH
), but most specimens contain some magnesium
, and (Ni,Mg)(SiO)(OH) is more realistic. There is a similar mineral called lizardite in which all the nickel is replaced by magnesium, formula Mg(SiO)(OH). These two minerals form a series, that is to say intermediate compositions are possible, with varying proportions of nickel to magnesium.
Pecoraite is another rare mineral with the same chemical formula as népouite, but a different structure; such minerals are said to be dimorphs of each other, in the same way as graphite is a dimorph of diamond. Népouite, lizardite and pecoraite are all members of the kaolinite-serpentine group.
Garnierite
is a green nickel
ore that formed as a result of weathering of ultramafic rocks, and that occurs in many nickel deposits worldwide. It is a mixture of various nickel and magnesium
phyllosilicates (sheet silicates), including népouite. Associated minerals include calcite
, chlorite
, goethite
, halloysite
, nontronite
, pimelite, quartz
, sepiolite
, serpentine, talc
and willemseite.
As well as the type locality in New Caledonia, it has been found in Australia, Austria, the Czech Republic, the Democratic Republic of Congo, Germany, Greece, Italy, Japan, Morocco, Poland, Russia, South Africa and the USA.
, b = 9.19 Å, c = 14.50 Å
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
silicate mineral which has the apple green colour typical of such compounds. It was named by E Glasser in 1907 after the place where it was first described (the type locality
Type locality (geology)
Type locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....
), the Népoui Mine, Népoui, Nouméa Commune, Northern Province, New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...
. The ideal formula is Ni
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
(Si
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
)(OH
Hydroxide
Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and a hydrogen atom held together by a covalent bond, and carrying a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, as a ligand, a nucleophile, and a...
), but most specimens contain some magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
, and (Ni,Mg)(SiO)(OH) is more realistic. There is a similar mineral called lizardite in which all the nickel is replaced by magnesium, formula Mg(SiO)(OH). These two minerals form a series, that is to say intermediate compositions are possible, with varying proportions of nickel to magnesium.
Pecoraite is another rare mineral with the same chemical formula as népouite, but a different structure; such minerals are said to be dimorphs of each other, in the same way as graphite is a dimorph of diamond. Népouite, lizardite and pecoraite are all members of the kaolinite-serpentine group.
Garnierite
Garnierite
Garnierite is a general name for a green nickel ore which is found in pockets and veins within weathered and serpentinized ultramafic rocks. It forms by lateritic weathering of ultramafic rocks and occurs in many nickel laterite deposits in the world. It is an important nickel ore, having a large...
is a green nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
ore that formed as a result of weathering of ultramafic rocks, and that occurs in many nickel deposits worldwide. It is a mixture of various nickel and magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
phyllosilicates (sheet silicates), including népouite. Associated minerals include calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
, chlorite
Chlorite group
The chlorites are a group of phyllosilicate minerals. Chlorites can be described by the following four endmembers based on their chemistry via substitution of the following four elements in the silicate lattice; Mg, Fe, Ni, and Mn....
, goethite
Goethite
Goethite , named after the German polymath Johann Wolfgang von Goethe, is an iron bearing oxide mineral found in soil and other low-temperature environments. Goethite has been well known since prehistoric times for its use as a pigment. Evidence has been found of its use in paint pigment samples...
, halloysite
Halloysite
Halloysite is a 1:1 aluminosilicate clay mineral with the empirical formula Al2Si2O54. Its main constituents are aluminium , silicon , and hydrogen . Halloysite typically forms by hydrothermal alteration of alumino-silicate minerals. It can occur intermixed with dickite, kaolinite, montmorillonite...
, nontronite
Nontronite
Nontronite is the iron rich member of the smectite group of clay minerals. Nontronites typically have a chemical composition consisting of more than ~30% Fe2O3 and less than ~12% Al2O3 . Nontronite generally does not exist in economic deposits like montmorillonite, although it is not an uncommon...
, pimelite, quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
, sepiolite
Sepiolite
Sepiolite is a clay mineral, a complex magnesium silicate, a typical formula for which is Mg4Si6O152·6H2O. It can be present in fibrous, fine-particulate, and solid forms....
, serpentine, talc
Talc
Talc is a mineral composed of hydrated magnesium silicate with the chemical formula H2Mg34 or Mg3Si4O102. In loose form, it is the widely-used substance known as talcum powder. It occurs as foliated to fibrous masses, its crystals being so rare as to be almost unknown...
and willemseite.
As well as the type locality in New Caledonia, it has been found in Australia, Austria, the Czech Republic, the Democratic Republic of Congo, Germany, Greece, Italy, Japan, Morocco, Poland, Russia, South Africa and the USA.
Structure
Space Group Ccm21. Unit Cell: a = 5.31 ÅÅngström
The angstrom or ångström, is a unit of length equal to 1/10,000,000,000 of a meter . Its symbol is the Swedish letter Å....
, b = 9.19 Å, c = 14.50 Å
| X-Ray Powder Diffraction | ||||||||
|---|---|---|---|---|---|---|---|---|
| d spacing | 7.31 | 4.55 | 3.63 | 2.89 | 2.50 | 2.31 | 2.20 | 1.53 |
| relative intensity | 10 | 5 | 9 | 6 | 7 | 4 | 4 | 6 |