talc

{{Infobox mineral | name = Talc | category = Phyllosilicate minerals | group = Pyrophyllite-Talc group | boxwidth = | boxbgcolor =#aad595 | image= Talc-177589.jpg | imagesize = 250px | caption = | formula = | IMAsymbol = Tlc | system = Monoclinic or triclinic | class = Either prismatic (2m) or pinacoidal () | symmetry = C2/c or C | unit cell = a = 5.291 Å, b = 9.173 Åc = 5.290 Å; α = 98.68°β = 119.90°, γ = 90.09°; Z = 2 ora = 5.287 Å, b = 9.158 Åc = 18.95 [Å], β = 99.3°; Z = 4 | strunz = 9.EC.05 | color = Light to dark green, brown, white, grey, colorless | habit = Foliated to fibrous masses, rare as platey to pyramidal crystals | twinning = | cleavage = Perfect on {001} basal cleavage | fracture = Flat surfaces (not cleavage), fracture in an uneven pattern | tenacity = Sectile | mohs = 1 (defining mineral) | luster = Waxy or pearly | refractive = nα = 1.538 – 1.550nβ = 1.589 – 1.594nγ = 1.589 – 1.600 | opticalprop = Biaxial (−) | birefringence = δ = 0.051 | pleochroism = Weak in dark varieties | streak = White jot to pearl black | gravity = 2.58–2.83 | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Translucent | fluorescence = Short UV: orange yellow; long UV: yellow | references = }}

Talc, or talcum, is a clay mineral composed of hydrated magnesium silicate, with the chemical formula . Talc in powdered form, often combined with corn starch, is used as baby powder. This mineral is used as a thickening agent and lubricant. It is an ingredient in ceramics, paints, and roofing material. It is a main ingredient in many cosmetics. It occurs as foliated to fibrous masses, and in an exceptionally rare crystal form. It has a perfect basal cleavage and an uneven flat fracture, and it is foliated with a two-dimensional platy form.