Oligoclase

Irradiation may turn colourless material blue if lead and water impurities are present (see amazonite). Oligoclase has also been reported to turn orange and green upon irradiation. 6 to 6.5Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references 2.62 to 2.67Walter Schumann, Gemstones of the world (2001) More from other references Perfect,GoodMichael O?Donoghue, Gems, Sixth Edition (2006) Perfect in one and good in another direction ConchoidalMichael O?Donoghue, Gems, Sixth Edition (2006) 1.538 to 1.550Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references Biaxial/-Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references 0.010Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references WeakMichael O?Donoghue, Gems, Sixth Edition (2006) Colourless to bluishWalter Schumann, Gemstones of the world (2001) More from other references Blue (moonstone), Rayleight scattering of light by lamellar structure. Red (sunstone), red lepidocrocite or hematite platelets give the aventurescenceW. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011) TransparentUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) Vitreous,PearlyWalter Schumann, Gemstones of the world (2001) On cleavage surfaces mother-of-pearl lustreMore from other references Pale brownish white, pale brownMichael O?Donoghue, Gems, Sixth Edition (2006) TriclinicWalter Schumann, Gemstones of the world (2001) More from other references As a major part of many rocks, especially igneous rocks such as granites, syenites and pegmatites. Also in intermediate lavas, schists and some amphibolites.Michael O?Donoghue, Gems, Sixth Edition (2006) Red hematite platelets (aventurism) - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 8 Oligoclase information at mindat.org