Download: … Microcline is identical to orthoclase in many physical properties, and can be distinguished by x-ray or optical examination. The really precise way is to use thin sections to determine the optical properties along the different crystallographic axes. Quartz is uniaxial positive with a low relief and low birefringence, thus ... Microcline. To link to this object, paste this link in email, IM or document To embed this object, paste this HTML in website. Microcline is the stable form below about 400 C. Orthoclase and sanidine are stable above 500 C and 900 C, respectively. Optical Properties : Microcline s tartan plaid twinning (a combination of albite and pericline twinning) is its most diagnostic. Microcline (Greek - small slope) has the same chemical composition as orthoclase but is classified in the triclinic crystal system. Upon cooling, orthoclase must rearrange its structure from monoclinic to triclinic. Optical Properties Qti l hittQuartz is commonly white to colourless in hand speciman and colourless in thin section. Microcline is the lowest temperature form of alkali feldspar. Optical Properties. Other, rare, related feldspar varieties include adularia and anorthoclase. Low relief and low 1st order birefringence – sometimes tin ggyed yellow. The blue-green feldspar amazonite is the only gem variety of microcline. When viewed under a polarizing microscope, microcline exhibits a minute multiple twinning which forms a grating-like structure that is unmistakable. Crystallography : Triclinic, a = 8.58, b = 12.96, c = 7.21, a = 89.7°, b = 115.97°, g = 90.87°, Z = 4; space group P1; point group 1. Uniaxial (Trigonal) positive and length fastlength fast. Microcline is identical to orthoclase in many physical properties; it can be distinguished by x-ray or optical examination; viewed under a polarizing microscope, microcline exhibits a minute multiple twinning which forms a grating-like structure that is unmistakable. The amateur has a few clues. Habit : Prismatic, stubby to elongate crystals are typical. Microcline (thin section) View Description. Its chemistry and atomic arrangement are variable, so optical properties vary as well. Fermion Index: Fermion Index = 0.01 Boson Index = 0.99 : Photoelectric: PE Microcline = 2.85 barns/electron U=PE Microcline x r electron = … When this happens, twinning usually results. Calculated Properties of Microcline : Electron Density: Bulk Density (Electron Density)=2.54 gm/cc note: Specific Gravity of Microcline =2.56 gm/cc. 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