Nacrite
A valid IMA mineral species - grandfathered
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About Nacrite
Formula:
Al2(Si2O5)(OH)4
Colour:
White, grey, yellowish, brownish, etc.
Lustre:
Pearly
Hardness:
2 - 2½
Crystal System:
Monoclinic
Member of:
Name:
From the French "nacre" (mother of pearl) alluding to its lustre.
Polymorph of:
de Ligny and Navrotsky (1999) showed that kaolinite is the thermodynamically stable phase and the polymorphs dickite, halloysite and nacrite are metastable phases mainly crystallising due to kinetic reasons.
Unique Identifiers
Mindat ID:
2826
Long-form identifier:
mindat:1:1:2826:0
Similar Names
| Natrite | A valid IMA mineral species | Na2CO3 |
| Nigrite | A variety of 'Bitumen' ['Petroleum'] |
IMA Classification of Nacrite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Al2Si2O5(OH)4
Classification of Nacrite
9.ED.05
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
Dana 7th ed.:
71.1.1.3
15.7
15 : Silicates of Aluminum
15 : Silicates of Aluminum
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 |
|---|---|---|
| Ncr | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Ncr | 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 Nacrite
Optical Data of Nacrite
Type:
Biaxial (-)
RI values:
nα = 1.557 nβ = 1.562 nγ = 1.563
2V:
Measured: 40° , Calculated: 48°
Max. Birefringence:
δ = 0.006
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:
Moderate
Dispersion:
r > v strong
Chemistry of Nacrite
Mindat Formula:
Al2(Si2O5)(OH)4
Element Weights:
Elements listed:
Crystallography of Nacrite
Crystal System:
Monoclinic
Class (H-M):
m - Domatic
Space Group:
Bb
Cell Parameters:
a = 5.14 Å, b = 8.94 Å, c = 14.4 Å
β = 113.7°
β = 113.7°
Ratio:
a:b:c = 0.575 : 1 : 1.611
Unit Cell V:
605.90 ų (Calculated from Unit Cell)
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0012238 | Nacrite | Zheng H, Bailey S W (1994) Refinement of the nacrite structure Clays and Clay Minerals 42 46-52 | 1994 | Red Mountain near Silverton, Colorado, USA | 0 | 293 | |
| 0012394 | Nacrite | Zhukhlistov A P (2008) Crystal structure of nacrite from the electron diffraction data Crystallography Reports 53 76-82 | 2008 | 0 | 293 | ||
| 0017961 | Nacrite | Hendricks S (1939) The Crystal Structure of Nacrite Al2 O3 * 2Si O2 * 2H2 O and the Polymorphism of the Kaolin Minerals. _cod_database_code 1011062 Zeitschrift fur Kristallographie 100 509-518 | 1939 | 0 | 293 | ||
| 0017977 | Nacrite | Gruner J (1933) The crystal structure of Nacrite and a comparison of certain optical properties of the caolin group with its structures _cod_database_code 1011080 Zeitschrift fur Kristallographie 85 345-354 | 1933 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.18 Å | (100) |
| 4.41 Å | (30) |
| 4.36 Å | (80) |
| 4.13 Å | (70) |
| 3.59 Å | (80) |
| 2.43 Å | (60) |
| 2.40 Å | (40) |
| 1.49 Å | (40) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 22 : Hydration and low-? subsurface aqueous alteration (see also #23) | |
| 24 : Authigenic minerals in terrestrial sediments (see also #17) | |
| 28 : Photo-alteration, pre-biotic | |
| Stage 5: Initiation of plate tectonics | <3.5-2.5 |
| 40 : Regional metamorphism (greenschist, amphibolite, granulite facies) | |
| 43 : Shear-induced minerals (including mylonite/slickensides) |
Type Occurrence of Nacrite
Synonyms of Nacrite
Other Language Names for Nacrite
Varieties of Nacrite
| Tianhuang Stone | A dense variety of nacrite, which is traded in China as a gemstone and is used for carvings. The material consists mainly of nacrite, but may also contain minor illite or dickite in varying proportions. The most valuable variety consists of golden yellow ... |
Relationship of Nacrite to other Species
Member of:
Other Members of Kaolinite Subgroup:
| Dickite | Al2(Si2O5)(OH)4 | Mon. m : Bb |
| Halloysite | Al2Si2O5(OH)4 · n(H2O) | Mon. m : Bb |
Common Associates
Associations Based on Photo Data:
| 14 photos of Nacrite associated with Quartz | SiO2 |
| 10 photos of Nacrite associated with Hematite | Fe2O3 |
| 8 photos of Nacrite associated with Calcite | CaCO3 |
| 6 photos of Nacrite associated with Cinnabar | HgS |
| 6 photos of Nacrite associated with Clinozoisite | (CaCa)(AlAlAl)O[Si2O7][SiO4](OH) |
| 5 photos of Nacrite associated with Fluorite | CaF2 |
| 5 photos of Nacrite associated with Goethite | Fe3+O(OH) |
| 4 photos of Nacrite associated with Ankerite | Ca(Fe2+,Mg)(CO3)2 |
| 4 photos of Nacrite associated with Cassiterite | SnO2 |
| 2 photos of Nacrite associated with Sphalerite | ZnS |
Related Minerals - Strunz-mindat Grouping
| 9.ED. | 'Clinochrysotile' | Mg3(Si2O5)(OH)4 |
| 9.ED.05 | Dickite | 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 | Népouite | Ni3Si2O5(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 |
Other Information
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 Nacrite
mindat.org URL:
https://www.mindat.org/min-2826.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 Nacrite
Reference List:
Ross, Clarence S., Kerr, Paul F. (1930) Dickite, a kaolin mineral. American Mineralogist, 15 (1) 34-39
Bailey, S. W. (1963) Polymorphism of the kaolin minerals. American Mineralogist, 48 (11-12) 1196-1209
Zheng, Hong (1994) Refinement of the Nacrite Structure. Clays and Clay Minerals, 42 (1) 46-52 doi:10.1346/ccmn.1994.0420106
de Ligny, Dominique; Navrotsky, Alexandra (1999) Energetics of kaolin polymorphs. American Mineralogist, 84 (4). p.506-516. doi:10.2138/am-1999-0404
Localities for Nacrite
Showing 170 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.
Algeria | |
| Singer et al. (2009) |
Arctic Ocean | |
| Marques et al. (2020) |
Argentina | |
| Jovic et al. (2011) |
Australia | |
| Francis (2010) |
| Francis (2010) |
Austria | |
| Niedermayr et al. (1995) |
| Schachinger et al. (2015) |
| Strasser (1989) |
Belgium | |
| Aderca (1962) +2 other references |
| Mélon et al. (1976) |
| Brown et al. (1974) +1 other reference | |
| Hatert et al. (2002) |
| Ledoux (1913) +1 other reference |
Bolivia | |
| Federico Ahlfeld and Jorge Munoz Reyes: Las Especies Minerales de Bolivia (Banco Minero de Bolivia, 1955) |
| Wilson (2001) |
| Kempff et al. (La Paz, 2009) |
| Cacho et al. (2019) | |
| Petrov et al. (2006) |
| Smith et al. (2001) |
Bosnia and Herzegovina | |
| Mudrinic et al. (1969) |
Bulgaria | |
| Sabeva et al. (2017) |
Canada | |
| Peatfield (n.d.) |
| Battler et al. (2013) |
| Alfredo Petrov specimen (ex- Vandall King) |
| Sabine (1983) |
| Horváth collection |
| Sabina (1983) | |
| Sabina (1983) |
| Horváth Collection - confirmed by ... |
Chile | |
| Lohmeier et al. (2025) |
China | |
| [var: Tianhuang Stone] Leifu Ren (1988) |
| Zheng Xia and Ningke Zhang (1986) |
| Zheng Xia and Ningke Zhang (1986) |
| Zhou et al. (2025) |
| Yang et al. (2022) |
| Mao et al. (2024) |
| Yuan et al. (2026) |
| Li et al. (2024) |
Czech Republic | |
| Vtělenský J. (1959) |
| Sejkora (1998) |
| X ray analysed |
| Duda |
DR Congo | |
| www.metafro.be (n.d.) +1 other reference |
Europe | |
| Quellmalz (1992) |
Finland | |
| von Knorring et al. (1952) |
France | |
| COUREAU |
| P. Le Roch collection |
| De Ascençao Guedes et al. (2001) |
| Michel Treillard collection |
| Berbain et al. (2000) |
| European Journal of Mineralogy +3 other references |
Georgia | |
| Şafak Utku Sönmez et al. (2022) |
Germany | |
| Walenta (1996) |
| Walenta (1992) |
| Kanka (1985) | |
| Müller (1984) |
| Weiß (1990) |
| Dill et al. (2010) |
| Weiß (1990) |
| Weiß (1990) |
| 54 +1 other reference |
| Rykart et al. (1978) +1 other reference |
| Kohout (2008) |
| Müller (2013) |
| Wittern (2001) |
| EDX/XRD confirmed by Günter Blaß |
| Weiß (1990) |
| Martin et al. (1994) |
| Wittern (2001) |
| Schlegel (1991) |
| Wittern (2001) | |
| Hajek (2010) |
| Wittern (2001) | |
| Wittern (2001) |
| Mineralogical Magazine 1908 15 : 124-127 |
| Uwe Ludwig specimen & photo |
| Baumann et al. (1997) |
| Frenzel (1874) |
| www.mineralienatlas.de (n.d.) |
| Wittern: "Mineralfundorte in ... |
| Wittern (2001) |
| Jahn (1999) |
| Frenzel (1874) |
| Witzke et al. (1998) |
| Wittern (2001) |
Guyana | |
| Mahdia Gold Corporation |
Hungary | |
| Koch (1985) |
Iran | |
| Ellahi et al. (2016) +1 other reference |
Italy | |
| Gallo (1973) |
| Gianluca Armellino |
| Daniel Lorenz |
| Ferretti et al. (2018) |
| Canal et al. (2012) |
| Gasparetto et al. (2014) |
| Erica Bittarello +3 other references |
Japan | |
| 米田哲朗. (1989) |
| Fujii et al. (1971) |
| Fujii et al. (1971) |
Kazakhstan | |
| Jermolenko (2002) |
Mexico | |
| Clay Miner. 29:452-453 (1981) | |
| Parker (2010) |
Namibia | |
| Cairncross (2005) |
| Medenbach (2001) +2 other references | |
Palau | |
| Miller et al. (1987) |
Peru | |
| Galdos et al. (2024) |
Poland | |
| Lis et al. (1986) |
| Lis et al. (1986) |
| www.kamienna-gora.eu (2020) |
| Lis et al. (1986) |
| Lis et al. (1986) |
| Lis et al. (1986) |
| Migaszewski et al. (2007) |
Portugal | |
| Oliveira et al. (2025) |
| Oliveira et al. (2025) |
Romania | |
| Onac et al. (1995) |
Serbia | |
| Zivanovic (2019) |
Slovakia | |
| Ďuďa R. et al. (1993) |
| Rojkovičová |
| Grecula (1995) |
| Koděra et al. (1986) |
| Koděra et al. (1986) |
| Koděra et al. (1986) | |
| Varček C. | |
| Ďuda et al. (1996) |
| Koděra et al. (1986) |
South Africa | |
| Cairncross et al. (1995) |
| Geyer (2008) |
South Korea | |
| G. Grundmann collection # 128 |
Spain | |
| Rewitzer et al. (2020) |
| Mendoza et al. (2006) |
| Cruz et al. (1997) |
| Perona et al. (2018) |
| Joan Abella i Creus (2008) |
| Calvo Rebollar (2018) | |
| Joan Abella i Creus (2008) |
| Sainz de Baranda Graf et al. (2023) |
Sweden | |
| Wilke (1997) |
| Sandström (2008) |
Taiwan | |
| Simmons et al. (2005) |
Turkey | |
| Yigit (2012) |
UK | |
| Fitch et al. (2022) |
| Day (1999) |
| |
| Claringbull (1952) |
Ukraine | |
| Pekov (1998) |
| Pavel M. Kartashov (n.d.) |
| |
USA | |
| azminerals.com |
| Anthony et al. (1995) |
| J. Lawrence Smith (1867) |
| - (2005) |
| Eckel et al. (1997) | |
| - (2005) | |
| Eckel et al. (1997) | |
| Eckel et al. (1997) |
| Eckel et al. (1997) | |
| Zheng (1994) |
| Januzzi et al. (1976) |
| Januzzi (1976) |
| Parker (2014) |
| Heinrich et al. (2004) |
| Castor et al. (2004) |
| Castor et al. (2004) |
| Northrop et al. (1996) |
| Miller (1971) |
| Piccione et al. (2019) |
| Dietrich (1985) |
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