Népouite
Phyllosilicate mineral in the serpentine subgroup
title: "Népouite" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["serpentine-subgroup", "nickel-minerals", "orthorhombic-minerals", "minerals-in-space-group-36"] description: "Phyllosilicate mineral in the serpentine subgroup" topic_path: "general/serpentine-subgroup" source: "https://en.wikipedia.org/wiki/Népouite" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Phyllosilicate mineral in the serpentine subgroup ::
::data[format=table title="Infobox mineral"]
| Field | Value |
|---|---|
| name | Népouite |
| category | Phyllosilicate minerals |
| group | Kaolinite-Serpentine group, serpentine subgroup |
| image | Népouite MHNT.MIN.2005.0.63.jpg |
| imagesize | 260px |
| caption | Népouite from the Népoui Mine, North Province, New Caledonia. Specimen size: 21 cm. |
| formula | |
| IMAsymbol | Npo |
| strunz | 9.ED.15 |
| dana | 71.1.2b.3 |
| system | Orthorhombic |
| class | pyramidal (mm2) |
| (same H-M symbol) | |
| symmetry | Ccm21 (no. 36) |
| color | bright green (typical of nickel bearing silicates) to yellowish or brownish green, depending on nickel content |
| habit | generally massive, also fibrous and microscopic pseudohexagonal platy crystals |
| cleavage | perfect on {001} |
| mohs | 2 to |
| luster | earthy to waxy, also pearly |
| streak | greenish white |
| diaphaneity | semitranslucent |
| gravity | 3.18 to 3.24 (measured) |
| opticalprop | biaxial (−) |
| refractive | nα = 1.600 – 1.630 nγ = 1.635 – 1.650 |
| birefringence | 0.035 |
| pleochroism | weak. X = green to yellow green Z = yellow-green |
| references | |
| :: |
| name = Népouite | category = Phyllosilicate minerals | group = Kaolinite-Serpentine group, serpentine subgroup | boxwidth = | image = Népouite MHNT.MIN.2005.0.63.jpg | imagesize = 260px | caption = Népouite from the Népoui Mine, North Province, New Caledonia. Specimen size: 21 cm. | formula = | IMAsymbol = Npo | molweight = | strunz = 9.ED.15 | dana = 71.1.2b.3 | system = Orthorhombic | class = pyramidal (mm2) (same H-M symbol) | symmetry = Ccm21 (no. 36) | color = bright green (typical of nickel bearing silicates) to yellowish or brownish green, depending on nickel content | habit = generally massive, also fibrous and microscopic pseudohexagonal platy crystals | cleavage = perfect on {001} | mohs = 2 to | luster = earthy to waxy, also pearly | streak = greenish white | diaphaneity = semitranslucent | gravity = 3.18 to 3.24 (measured) | density = | opticalprop = biaxial (−) | refractive = nα = 1.600 – 1.630 nγ = 1.635 – 1.650 | birefringence = 0.035 | pleochroism = weak. X = green to yellow green Z = yellow-green | 2V = | dispersion = | references =
Népouite is a rare nickel silicate mineral which has the apple green color typical of such compounds. It was named by the French mining engineer Edouard Glasser in 1907 after the place where it was first described (the type locality), the Népoui Mine, , Poya Commune, North Province, New Caledonia. The ideal formula is , but most specimens contain some magnesium, and is more realistic. There is a similar mineral called lizardite (named after the Lizard Complex in Cornwall, England) in which all of the nickel is replaced by magnesium, formula . These two minerals form a series; 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, 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 is present in Australia, Austria, the Czech Republic, the Democratic Republic of Congo, Germany, Greece, Italy, Japan, Morocco, Poland, Russia, South Africa and the United States.
Structure
Space group Ccm21. Unit cell: a = 5.31 Å, b = 9.19 Å, c = 14.50 Å ::data[format=table title="X-ray powder diffraction data"]
| d spacing | relative intensity |
|---|---|
| 7.31 | 4.55 |
| 10 | 5 |
| :: |
References
References
- Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
- http://rruff.geo.arizona.edu/doclib/hom/nepouite.pdf Handbook of Mineralogy
- http://www.mindat.org/min-2882.html Mindat.org
- http://www.webmineral.com/data/Nepouite.shtml Webmineral data
- M. E. Glaser. (1907). "Note sur une espèce minérale nouvelle, la népouite, silicate hydraté de nickel et de magnésie. Bulletin de Minéralogie. Année 1907, 30 (1), pp. 17–28. – Sur le site de Persée". persee.fr.
- "Lizardite-Népouite Series".
- American Mineralogist (1975): 60: 863–871
- Dana’s New Mineralogy, Eighth Edition, 1997, Gaines et al., Wiley.
- Mineralogical Record 38-5, page 384
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