{{Short description|Phyllosilicate mineral}} {{infobox mineral | name = Stilpnomelane | boxwidth = | image = Stilpnomelane-217448.jpg | alt = | caption = | category = Phyllosilicate minerals | group = Stilpnomelane group | formula = {{chem2|K(Fe(2+),Mg,Fe(3+))8(Si,Al)12(O,OH)27*n(H2O)}} | IMAsymbol = Stp<ref>{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|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}}</ref> | molweight = | strunz = 9.EG.40 | dana = | system = Triclinic | class = Pinacoidal ({{overline|1}}) <br/><small>(same H-M symbol)</small> | symmetry = ''P''{{overline|1}} | unit cell = a = 21.72&nbsp;Å, b = 21.72&nbsp;Å <br/>c = 17.4&nbsp;Å; α = 124.14° <br/>β = 95.86°, γ = 120°; Z&nbsp;=&nbsp;6 | color = Black, greenish black, yellowish bronze, greenish bronze | colour = | habit = Platey, scaly and fibrous with comb structures; radiating groups | twinning = | cleavage = Perfect on {001}, imperfect on {010} | fracture = | tenacity = Brittle | mohs = 3–4 | luster = Vitreous to dull | streak = Gray white | diaphaneity = Subtranslucent to opaque | gravity = 2.77 – 2.96 | density = | polish = | opticalprop = Biaxial (−) | refractive = n<sub>α</sub> = 1.543 – 1.634 n<sub>β</sub> = 1.576 – 1.745 n<sub>γ</sub> = 1.576 – 1.745 | birefringence = δ = 0.033 – 0.111 | pleochroism = X: bright golden yellow to pale yellow Y and Z: deep reddish brown, to deep green to nearly black | 2V = 0–40 measured | dispersion = None | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | references = <ref name=Handbook>[http://www.handbookofmineralogy.org/pdfs/Stilpnomelane.PDF Handbook of Mineralogy]</ref><ref name=Mindat>[http://www.mindat.org/min-3789.html Stilpnomelane on Mindat]</ref><ref name=Webmin>[http://www.webmineral.com/data/Stilpnomelane.shtml Stilpnomelane on Webmineral]</ref> }}

'''Stilpnomelane''' is a phyllosilicate mineral. It has the chemical formula {{chem2|K(Fe(2+),Mg,Fe(3+))8(Si,Al)12(O,OH)27*n(H2O)}}.<ref name=Webmin/>

Stilpnomelane occurs associated with banded iron formations. It is a metamorphic mineral associated with the blueschist and greenschist facies.<ref name=Handbook/>

It was first described in 1827 for an occurrence in Moravia in the Czech Republic. The name is derived from the Greek {{Transliteration|grc|stilpnos}} for shining, and {{Transliteration|grc|melanos}} for black.<ref name=Mindat/>

==References== {{Reflist}}

{{Authority control}} {{Phyllosilicates}}

Category:Triclinic minerals Category:Minerals in space group 2 Category:Stilpnomelane group

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