rubicline

{{Infobox mineral | name = Rubicline | category = Tectosilicate minerals | group = Feldspar group | series = Alkali feldspar series | boxwidth = | boxbgcolor = | image = Rubicline.jpg | imagesize = | alt = | caption = | formula = (Rb, K)[AlSi3O8] | IMAsymbol = Rub | IMAstatus = Approved (1998) | molweight = 313.11 g/mol | strunz = 9.FA.30 | dana = | system = Monoclinic | class = Prismatic (2/m) | symmetry = B2/m (no. 12) | color = Colorless | habit = | twinning = | cleavage = {001} | fracture = | tenacity = | mohs = 6 | luster = Vitreous | streak = | diaphaneity = Transparent | gravity = | density = 2.8 g/cm3 | polish = | opticalprop = biaxial | refractive = nα = 1.520 nβ = 1.524 nγ = 1.527 | birefringence = δ = 0.007 | pleochroism = | 2V = | dispersion = Strong | extinction = | length fast/slow = | fluorescence= | absorption = | melt = | fusibility = | diagnostic = | solubility = | other = Radioactive | alteration = | references = }}

Rubicline, also referred to as Rb-microcline, is the rubidium analogue of microcline, an important tectosilicate mineral. Its chemical formula is (Rb, K)[AlSi3O8] with an ideal composition of RbAlSi3O8. Chemical analysis by electron microprobe indicated the average weight of the crystal is 56.66% SiO2, 16.95% Al2O3, and 23.77% Rb2O, along with trace amounts of caesium oxide (Cs2O) and iron(III) oxide (Fe2O3).