stilpnomelane

{{infobox mineral | name = Stilpnomelane | boxwidth = | image = Stilpnomelane-217448.jpg | alt = | caption = | category = Phyllosilicate minerals | group = Stilpnomelane group | formula = | IMAsymbol = Stp | molweight = | strunz = 9.EG.40 | dana = | system = Triclinic | class = Pinacoidal () (same H-M symbol) | symmetry = P | unit cell = a = 21.72 Å, b = 21.72 Å c = 17.4 Å; α = 124.14° β = 95.86°, γ = 120°; Z = 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 = nα = 1.543 – 1.634 nβ = 1.576 – 1.745 nγ = 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 = }}

Stilpnomelane is a phyllosilicate mineral. It has the chemical formula .