Népouite
A valid IMA mineral species - grandfathered
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About Népouite
Formula:
Ni3Si2O5(OH)4
Colour:
Intense dark green to dull green.
Lustre:
Waxy
Hardness:
2 - 2½
Specific Gravity:
3.24
Crystal System:
Orthorhombic
Member of:
Name:
Named after type locality.
Dimorph of:
Name Encoding
ASCII-7:
Nepouite
Unique Identifiers
Mindat ID:
2882
Long-form identifier:
mindat:1:1:2882:6
Similar Names
| Nahpoite | A valid IMA mineral species | Na2(PO3OH) |
| Neapite | A synonym of 'Apatite nephelinolite' | |
| Nipeiite-(Ce) | A valid IMA mineral species - pending publication | Ce9Fe3+(SiO4)6[SiO3(OH)](OH)3 |
IMA Classification of Népouite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Ni2+3Si2O5(OH)4
First published:
1907
Classification of Népouite
9.ED.15
9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets
9 : SILICATES (Germanates)
E : Phyllosilicates
D : Phyllosilicates with kaolinite layers composed of tetrahedral and octahedral nets
71.1.2b.3
71 : PHYLLOSILICATES Sheets of Six-Membered Rings
1 : Sheets of 6-membered rings with 1:1 layers
71 : PHYLLOSILICATES Sheets of Six-Membered Rings
1 : Sheets of 6-membered rings with 1:1 layers
14.26.3
14 : Silicates not Containing Aluminum
26 : Silicates of Ni
14 : Silicates not Containing Aluminum
26 : Silicates of Ni
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Npo | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Npo | Warr (2020) | Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30 |
Physical Properties of Népouite
Waxy
Transparency:
Translucent, Opaque
Colour:
Intense dark green to dull green.
Streak:
Greenish white
Hardness:
2 - 2½ on Mohs scale
Tenacity:
Sectile
Cleavage:
Poor/Indistinct
Fracture:
Irregular/Uneven
Density:
3.24 g/cm3 (Measured) 3.26(13) g/cm3 (Calculated)
Optical Data of Népouite
Type:
Biaxial (-)
RI values:
nα = 1.622 nβ = 1.576 - 1.579 nγ = 1.635 - 1.650
Birefringence:
0.027
Max. Birefringence:
δ = 0.013 - 0.028
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Dispersion:
r > v medium
Pleochroism:
Weak
Comments:
X = dark green; Z = yellow-green
Chemistry of Népouite
Mindat Formula:
Ni3Si2O5(OH)4
Element Weights:
Elements listed:
Crystallography of Népouite
Crystal System:
Orthorhombic
Cell Parameters:
a = 5.29(2) Å, b = 9.17(3) Å, c = 7.26(2) Å
Ratio:
a:b:c = 0.577 : 1 : 0.792
Unit Cell V:
352.18 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Rarely as crude pseudohexagonal vermiform crystals, to 1 cm, usually massive.
Comment:
Probably orthorhombic. Point Group: n.d.; Space Group: n.d.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.31 Å | (100) |
| 4.55 Å | (50b) |
| 3.63 Å | (90) |
| 2.894 Å | (60) |
| 2.501 Å | (70) |
| 2.321 Å | (40) |
| 1.530 Å | (60) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 5: Initiation of plate tectonics | <3.5-2.5 |
| 38 : Ophiolites | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] |
Geological Setting:
alteration of ultramafic rocks
Type Occurrence of Népouite
Geological Setting of Type Material:
Alteration product of nickel-rich ultramafic rocks.
Associated Minerals at Type Locality:
Synonyms of Népouite
Other Language Names for Népouite
Relationship of Népouite to other Species
Member of:
Other Members of Serpentine Subgroup:
| Amesite | Mg2Al(AlSiO5)(OH)4 | Tric. 1 : P1 |
| Antigorite | Mg3(Si2O5)(OH)4 | Mon. m : Bm |
| Berthierine | (Fe2+,Fe3+,Al)3(Si,Al)2O5(OH)4 | Mon. m : Bm |
| Brindleyite | (Ni,Al)3(Si,Al)2O5(OH)4 | Mon. |
| Caryopilite | Mn2+3Si2O5(OH)4 | Mon. |
| Chrysotile | Mg3(Si2O5)(OH)4 | Mon. m : Bb |
| Cronstedtite | Fe2+2Fe3+((Si,Fe3+)2O5)(OH)4 | Trig. 3m : P31m |
| Fraipontite | (Zn,Al)3((Si,Al)2O5)(OH)4 | Mon. |
| Guidottiite | Mn2Fe3+(Fe3+SiO5)(OH)4 | Hex. 6 : P63 |
| Kellyite | Mn2+2Al(AlSiO5)(OH)4 | Hex. 6 : P63 |
| Lizardite | Mg3(Si2O5)(OH)4 | Trig. 3m : P31m |
| Pecoraite | Ni3(Si2O5)(OH)4 | Mon. |
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 5 photos of Népouite associated with Trevorite | Ni2+Fe3+2O4 |
| 3 photos of Népouite associated with Jaipurite | CoS |
| 3 photos of Népouite associated with Maucherite | Ni11As8 |
| 3 photos of Népouite associated with Millerite | NiS |
| 3 photos of Népouite associated with Jamborite | Ni2+1-xCo3+x(OH)2-x(SO4)x · nH2O |
| 3 photos of Népouite associated with Goethite | Fe3+O(OH) |
| 3 photos of Népouite associated with Serpentine Subgroup | D3[Si2O5](OH)4 |
| 2 photos of Népouite associated with Vaesite | NiS2 |
| 2 photos of Népouite associated with Quartz | SiO2 |
| 2 photos of Népouite associated with Uraninite | UO2 |
Related Minerals - Strunz-mindat Grouping
| 9.ED. | 'Clinochrysotile' | Mg3(Si2O5)(OH)4 |
| 9.ED.05 | Dickite | Al2(Si2O5)(OH)4 |
| 9.ED.05 | Nacrite | Al2(Si2O5)(OH)4 |
| 9.ED.05 | Kaolinite | Al2(Si2O5)(OH)4 |
| 9.ED.05 | Odinite | (Fe,Mg,Al,Fe,Ti,Mn)2.4((Si,Al)2O5)(OH)4 |
| 9.ED.10 | Halloysite | Al2Si2O5(OH)4 · n(H2O) |
| 9.ED.10 | Hisingerite | Fe3+2(Si2O5)(OH)4 · 2H2O |
| 9.ED.10 | 'Hydrohalloysite' | Al2Si2O5(OH)4 · 2H2O |
| 9.ED.15 | Antigorite | Mg3(Si2O5)(OH)4 |
| 9.ED.15 | Brindleyite | (Ni,Al)3(Si,Al)2O5(OH)4 |
| 9.ED.15 | Fraipontite | (Zn,Al)3((Si,Al)2O5)(OH)4 |
| 9.ED.15 | Pecoraite | Ni3(Si2O5)(OH)4 |
| 9.ED.15 | Guidottiite | Mn2Fe3+(Fe3+SiO5)(OH)4 |
| 9.ED.15 | Lizardite | Mg3(Si2O5)(OH)4 |
| 9.ED.15 | Berthierine | (Fe2+,Fe3+,Al)3(Si,Al)2O5(OH)4 |
| 9.ED.15 | Kellyite | Mn2+2Al(AlSiO5)(OH)4 |
| 9.ED.15 | Cronstedtite | Fe2+2Fe3+((Si,Fe3+)2O5)(OH)4 |
| 9.ED.15 | Caryopilite | Mn2+3Si2O5(OH)4 |
| 9.ED.15 | Amesite | Mg2Al(AlSiO5)(OH)4 |
| 9.ED.15 | Greenalite | (Fe2+,Fe3+)2-3Si2O5(OH)4 |
| 9.ED.15 | Manandonite | Li2Al4(Si2AlB)O10(OH)8 |
| 9.ED.20 | Chrysocolla | Cu2-xAlx(H2-xSi2O5)(OH)4 · nH2O, x < 1 |
| 9.ED.20 | Neotocite | (Mn,Fe)SiO3 · H2O (?) |
| 9.ED.20 | Allophane | (Al2O3)(SiO2)1.3-2 · 2.5-3H2O |
| 9.ED.20 | Imogolite | Al2SiO3(OH)4 |
| 9.ED.25 | Bismutoferrite | Fe3+2Bi(SiO4)2(OH) |
| 9.ED.25 | Chapmanite | Fe3+2Sb3+(Si2O5)O3(OH) |
| 9.ED.30 | 'Pianlinite' | Al2Si2O6(OH)2 |
Fluorescence of Népouite
Not fluorescent in UV
Other Information
Magnetism:
Non-Magnetic
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Népouite
mindat.org URL:
https://www.mindat.org/min-2882.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Népouite
Reference List:
Glasser, Édouard (1907) Note sur une espèce minérale nouvelle, la népouite, silicate hydraté de nickel et de magnésie. Bulletin de Minéralogie, 30 (1) 17-28 doi:10.3406/bulmi.1907.2797
Brindley, G.W., Wan, Hsien Ming (1975) Compositions, structures, and thermal behavior of nickel-containing minerals in the lizardite-nepouite series. American Mineralogist, 60 (9-10) 863-871
Bayliss, Peter (1981) Unit cell data of serpentine group minerals. Mineralogical Magazine, 44 (334) 153-156 doi:10.1180/minmag.1981.044.334.06
Localities for Népouite
Showing 79 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Albania | |
| Thorne et al. (2012) |
Australia | |
| RRUFF Project Specimen ID: R050268 |
| Nickel et al. (1977) |
| Nickel et al. (1993) +1 other reference |
| Sue Koepke collection via Jiri Just |
| Grguric (2003) |
Austria | |
| Walter et al. (2025) +1 other reference |
| Niedermayr et al. (1995) |
Burundi | |
| The Royal Museum for Central Africa (RMCA) +1 other reference |
Canada | |
| Escayola et al. (2011) |
| Reiner Mielke 2017 |
China | |
| Wang et al. (2023) |
| Kaiji Yu (1981) |
Czech Republic | |
| |
| Pelíšek |
Dominican Republic | |
| Villanova-de-Benavent et al. (2014) |
| Lavinsky (n.d.) | |
DR Congo | |
| Gauthier et al. (1989) |
France | |
| Brindley et al. (1975) | |
| Dana 6:A2:75. +1 other reference |
| Berger et al. (2011) +1 other reference |
| Dana 6:A2:75. +1 other reference |
| Dana 6:A2:75. +1 other reference |
| C.R.Acad.Sci.Paris (1906) +1 other reference |
| Dana 6:A2:75. +1 other reference |
| Dana 6:A2:75. +1 other reference |
| Mineralogical Society of America - ... | |
| Vale SA |
| Onac (2025) |
Germany | |
| Wittern (2001) |
| XRD and SEM-EDX analysis (T. Witzke) |
Greece | |
| |
Indonesia | |
| Wei Fu et al. (2010) |
| Taixu Luo (2008) |
Italy | |
| Piccoli (2002) +1 other reference |
| Piccoli et al. (2007) |
| Gennaro (1931) +2 other references | |
| Piccoli et al. (2007) |
| Piccoli et al. (2007) |
| Ciriotti et al. (2023) +1 other reference |
| Lecca et al. (2022) |
Japan | |
| Matsubara (1996) |
| Go Ito +1 other reference |
Kazakhstan | |
| Pavel M. Kartashov analytical data 2019 |
Morocco | |
| Favreau et al. (2006) |
North Macedonia | |
| Spasovski et al. (2009) |
| Spasovski et al. (2009) | |
Norway | |
| Engvoldsen et al. (1991) +1 other reference |
Poland | |
| Spangenberg et al. (1949) |
| Spangenberg et al. (1949) | |
Portugal | |
| Marques de Sá et al. (2010) |
Russia | |
| Talovina et al. (2008) +2 other references |
| Mikhailov (2000) |
South Africa | |
| Cairncross et al. (1995) |
| De Waal et al. (1974) +2 other references |
South Korea | |
| Song et al. (1995) |
Spain | |
| Romero Silva (2003) |
| Romero Silva (2003) |
| Romero Silva (2003) | |
| Romero Silva (2003) |
| Colección Juan A.M. Barnestein. |
| Calvo Rebollar (2018) |
| Romero Silva (2003) |
| Joan Abella i Creus specimens +1 other reference |
USA | |
| Murdoch (1966) +2 other references |
| Pemberton (1983) +1 other reference |
| Pemberton (1983) +1 other reference |
| Clark (1956) +3 other references |
| Montoya et al. (1963) | |
| Pemberton (1983) |
| Morton (1977) +2 other references |
| Bradley (1941) +2 other references |
| Bradley (1938) +3 other references |
| Cooper et al. (1986) |
| Goodwin (1958) +2 other references |
| Excalibur Mineral Corporation - Rare ... |
| Genth (1891) |
| Conley (1958) |
| Genth (1891) |
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Népoui Mine, Pouembout, Northern Province, New Caledonia, France