triploidite

{{Infobox mineral | name = Triploidite | boxwidth = | boxbgcolor = | image = Triploidite-199681.jpg | imagesize = 200px | alt = | caption = Radial reddish triploidite from the Branchville Quarry, Branchville, Fairfield County, Connecticut, US (7.0 x 4.8 x 2.6 cm) | category = Phosphate minerals | formula = | IMAsymbol = Tpd | molweight = | strunz = 8.BB.15 | dana = | system = Monoclinic | class = Prismatic (2/m) (same H-M symbol) | symmetry = P21/a | unit cell = a = 12.36 Å, b = 13.27 Å c = 9.94 Å; β = 108.23°; Z = 16 | color = Red-brown, light pink, yellow-brown; light pink to light brown in transmitted light. | colour = | habit = Elongated and striated prismatic crystals; fibrous: columnar to spherulitic | twinning = | cleavage = On {010}, good; on {120}, fair; on {110}, very poor. | fracture = Uneven to subconchoidal | tenacity = | mohs = – 5 | luster = Adamantine, vitreous, greasy | streak = White, off-white. | diaphaneity = Transparent, translucent | gravity = 3.70 measured | density = | polish = | opticalprop = Biaxial (+) | refractive = nα = 1.725 nβ = 1.726 nγ = 1.730 | birefringence = δ = 0.005 | pleochroism = Weak | 2V = | dispersion = r > v strong | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = Soluble in acids. | impurities = | alteration = | other = | prop1 = | prop1text = | references = }}

Triploidite is an uncommon manganese iron phosphate mineral with formula: . It crystallizes in the monoclinic crystal system and typically occurs as elongated and striated slender prisms which may be columnar to fibrous. Its crystals may be pinkish to yellowish brown or red-orange.