jimthompsonite

{{Infobox mineral | name = Jimthompsonite | image = Jimthompsonite-chain.png | imagesize = | alt = | caption = Jimthompsonite structure | category = Inosilicates | formula = | IMAsymbol = Jim | strunz = 9.DF.05 | system = Orthorhombic | class = Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) | symmetry = Pbca | unit cell = a = 18.626, b = 27.23 c = 5.297 [Å]; Z = 8 | molweight = | color = Colorless to very light pinkish brown | colour = | habit = Radiating sprays and fibrous intergrowths | twinning = | cleavage = Perfect on {210} with 38° and 142° intersecting angle | fracture = | tenacity = | mohs = 2–2.5 | luster = | streak = | diaphaneity = | gravity = 3.02 (calculated) | density = | polish = | opticalprop = Biaxial (−) | refractive = nα = 1.605 nβ = 1.626 nγ = 1.633 | birefringence = δ = 0.028 | pleochroism = | 2V = 62° measured | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }}

Jimthompsonite is a magnesium iron silicate mineral with chemical formula . It is a triple chain silicate (or inosilicate) along with clinojimthompsonite and chesterite. They were described in 1977 by Burham and Veblen. They attracted great mineralogical attention because they were the first examples of new chain silicate structures among a large group known as biopyriboles whose name is derived from the words biotite, pyroxene, and amphiboles.