Extinction Angles
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“Maximum extinction angles in the Pyroxene and Amphibole groups. Solid lines indicate extinction angles from c to c; broken lines from c to a. The extinction angle in an amphibole is generally less than 23 degrees; in a pyroxene it is generally greater. “ -Johannsen, 1908
Keywords
rock-forming minerals, crystal optics, extinction angles, pyroxene group, amphibole group, monoclinic pyroxene separationGalleries
Miscellaneous OpticsSource
Albert Johannsen A Key for the Determination of Rock-Forming Minerals in Thin Sections (New York, NY: John Wiley & Sons, 1908)
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