fluorellestadite

{{Infobox mineral | name = Fluorellestadite | category = Nesosilicates Apatite structural group | image = Ellestadite-(F)-Calcite-215134.jpg | imagesize = 260px | caption = Fluorellestadite on blue calcite from the Crestmore Quarries, California, US | formula = Ca10(SiO4)3(SO4)3F2 | IMAsymbol = Fel | molweight = 503.55 g/mol | strunz = 9.AH.25 (10 ed) 8/B.27-10 (8 ed) | dana = 52.04.09.03 | system = Hexagonal | class = Dipyramidal (6/m) H-M symbol: (6/m) | symmetry = P63/m | color = Light red, yellow, bluish green or colorless | habit = Acicular or hexagonal prismatic crystals, and fine-grained aggregates | twinning = | cleavage = Imperfect on {0001} | fracture = Conchoidal | tenacity = Very brittle | mohs = | luster = Sub-resinous to vitreous | refractive = nω = 1.638(2), nε = 1.632(2); nω = 1.655, nε = 1.650 | opticalprop = Uniaxial (-) | birefringence = | pleochroism = | streak = White with a weak bluish tint | gravity = 3.03 to 3.07 | melt = | fusibility = | diagnostic = | solubility = Easily soluble in dilute hydrochloric and nitric acids | diaphaneity = Transparent to translucent | other = Sometimes fluorescent. Not radioactive. | references = }}

Fluorellestadite is a rare nesosilicate of calcium, with sulfate and fluorine, with the chemical formula Ca10(SiO4)3(SO4)3F2. It is a member of the apatite group, and forms a series with hydroxylellestadite.