Nacrite

{{short description|Phyllosilicate mineral: group of kaolinite}}

{{Infobox mineral

| name = Nacrite

| image = Nacrite - Mineralogisches Museum Bonn1.jpg

| alt =

| caption = Nacrite, "Frohe Hoffnung"-shaft, Wildental, Ore Mountains

| category = Phyllosilicates
Kaolinite-serpentine group

| formula = Al₂Si₂O₅(OH)₄

| IMAsymbol = Ncr{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|url=https://www.cambridge.org/core/journals/mineralogical-magazine/article/imacnmnc-approved-mineral-symbols/62311F45ED37831D78603C6E6B25EE0A|journal=Mineralogical Magazine|volume=85|issue=3 |pages=291–320|doi=10.1180/mgm.2021.43 |bibcode=2021MinM...85..291W |s2cid=235729616 |doi-access=free}}

| molweight =

| strunz = 9.ED.05

| system = Monoclinic

| class = Domatic (m)
(same H-M symbol)

| symmetry = Cc

| unit cell =

| color =

| colour =

| habit =

| twinning =

| cleavage =

| fracture =

| tenacity =

| mohs =

| luster =

| streak =

| diaphaneity =

| gravity =

| density =

| polish =

| opticalprop =

| refractive =

| birefringence =

| pleochroism =

| 2V =

| dispersion =

| extinction =

| length fast/slow =

| fluorescence =

| absorption =

| melt =

| fusibility =

| diagnostic =

| solubility =

| impurities =

| alteration =

| other =

| prop1 =

| prop1text =

| references = [http://www.mindat.org/min-2826.html Mindat Data sheet][http://www.webmineral.com/data/Nacrite.shtml Webmineral data]

}}

Nacrite Al₂Si₂O₅(OH)₄ is a clay mineral that is polymorphous (or polytypic) with kaolinite.{{Cite web |title=Nacrite |url=https://soilsfacstaff.cals.wisc.edu/facstaff/barak/virtual_museum/nacrite/nacrite_tx.html |access-date=2024-12-18 |website=soilsfacstaff.cals.wisc.edu}} {{Cite web |title=Nacrite |url=https://www.mindat.org/min-2826.html |access-date=2024-12-18 |website=www.mindat.org}} It crystallizes in the monoclinic system. X-ray diffraction analysis is required for positive identification.

Nacrite was first described in 1807 for an occurrence in Saxony, Germany. The name is from nacre in reference to the dull luster of the surface of nacrite masses scattering light with slight iridescences resembling those of the mother of pearls secreted by oysters.