amarantite

{{Infobox mineral | name = Amarantite | boxwidth = | boxbgcolor = | image = Amarantite - Javir-e-Sagand, Yazd Province, Iran.jpg | imagesize = 260px | alt = | caption = | category = Sulfate minerals | formula = Fe3+2O(SO4)2·7H2O |IMAsymbol=Ama | molweight = | strunz = 7.DB.30 | dana = | system = Triclinic | class = Pinacoidal () (same H-M symbol) | symmetry = P | unit cell = a = 8.9, b = 11.56 c = 6.64 [Å]; α = 95.55° β = 90.52°, γ = 97.42°; Z = 2 | color = Amaranth-red to brownish red, orange-red | colour = | habit = As radiating or matted aggregates of needles; may be columnar or bladed | twinning = | cleavage = Perfect on {010} and {100} | fracture = | tenacity = Brittle | mohs = | luster = Vitreous | streak = Lemon-yellow | diaphaneity = Transparent | gravity = 2.189–2.286 | density = | polish = | opticalprop = Biaxial (−) | refractive = nα = 1.516 nβ = 1.598 nγ = 1.621 | birefringence = δ = 0.105 | pleochroism = X = colorless; Y = pale yellow; Z = reddish brown | 2V = Measured: 30° | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }}

Amarantite is an amaranth-red to brownish mineral with the general formula of Fe3+2O(SO4)2·7H2O or Fe3+SO4(OH)·3H2O.