Transmitted Light
Pale green colors, may be yellowish. Amphibole, monoclinic, long prisms, fibers. Basal rhombic sections with 2 cleavages at 56-124º. In XPL, 1st and 2nd order colors. Extinction 10-15º, ES(+), frequent twins and zoning. B(-) with 2V of 80º. Mineral common in many types of rock. One image in PPL, the other one in XPL.
Pale green colors with weak pleochroism. Monoclinic. Common as a metamorphic mineral or alteration product. Very small lamellae, fibers or masses. In XPL anomalous colors: blue (berlin blue) or brown (leather brown), bluish-gray or purple. 0-9º extinction, unmottled. ES(+/-), B(+/-).
Pleochroic from light green to yellow-green or blue-green. Monoclinic, moderate relief, forms submicroscopic crystal aggregates. In XPL, the color is almost the same. Simulate parallel extinction. B(-). It occurs almost exclusively in cavities and fractures of volcanic rocks.
Pleochroic between green, yellow, olive and blue-green. In XPL, it continues with the green colors. Almost parallel extinction. B(-). Similar to celadonite. It forms rounded aggregates of submicroscopic crystals in sediments and sedimentary rocks of marine origin. One image in PPL, the other one in XPL.
Pleochroic between colorless, lime green, pale green, pale yellow, yellow-green and brown-green. Monoclinic, high relief. Granular, columnar, acicular. Basal sections are rhombic. 1 perfect cleavage. In XPL, intense and zoned anomalous colors. Paralell or oblique extinction. ES(+/-), B(-), 2V = 64-90º. Very common mineral, sometimes extremely fine grained.
Weak to moderate pleochroism between colorless, yellowish, light green and blue-green. Monoclinic. Lamellar, acicular, fibrous. Medium-high relief, 2 good cleavages. In CPL, colors between 1st and 2nd order or anomalous (indigo blue and leather brown). ES(+/-), Twins/zoning common, B(+), 2V 7º-110º.
Usually colorless, may have pale green to pink pleochroism. Short prisms of square section. Orthorhombic. Perfect {110} cleavage; basal sections with 2 cleavages at 89º. Extinction paralell, basal sections with symmetrical extinction. ES(-). Black carbon inclusions common. B(-), 2V:71-86°.
Usually colorless, but may have pale green, brown, yellow, or bluish pleochroism. Medium-high relief. Pyroxene, monoclinic, with 2 cleavages at ~90º in the basal sections. Oblique extinction (35-48º). ES(+). Twins common. B(+), 2V from 25-61°. Identical to diopside and pigeonite!
Usually colorless, but can be pale green in color with very weak pleochroism. Pyroxene, monoclinic. Medium to high relief. 2 cleavages at ~90º in basal sections. Granular to short prismatic. In CPL, colors up to 2nd order orange. Extinction 38-48º, B(+), 2V 58-62º. Identical to augite and pigeonite!
Usually colorless, can be pale, yellow-green to brownish-green in color. Pyroxene, monoclinic. Medium-high relief, typically granular and anhedral, usually in the rock matrix. In CPL, intense 2nd order colors. Oblique extinction from 37-44º, B(+) with 2V from 0-30º. Identical do augite and diopside!
Usually colorless, may be pleochroic to very pale green. Pyroxene, Monoclinic. High relief, in CPL colors up to 3rd order. Oblique extinction, common twins, B(+). Restricted to metamorphic rocks of eclogite facies (eclogites, kimberlites, ophiolites, blueschists). Similar to other clinopyroxenes!
Usually colorless, but can be pleochroic between pale green to pale brown. Monoclinic, it is a rare amphibole. Forms clusters of prismatic crystals. In the basal section (rhombic!), 2 cleavages at 56/124º. Extinction 15-21º. In XPL, colors up to 2nd and 3rd order. ES(+), B(+/-).
Usually colorless, but may be weakly pleochroic in green, yellow, violet, brown, or blue. Orthorhombic. Granular or tabular habit, forms radiated aggregates. In PPL, medium relief and several cleavages. In XPL, gray to straw yellow, ES(+) and parallel extinction. Twins rare, zonation absent. B(+).
Usually pleochroic in red-brown, but can be in green colors. Zoning common. Monoclinic with high relief, no visible cleavage. Anhedral or tabular grains. In CPL, colors up to 3rd order. Pleochroic (black) halos are possible, may be metamictic. Twins common. B(-/+). Similar to brown hornblende.
Usually pleochroic between pinkish and colorless, but may be pale green. Pyroxene, orthorhombic. Short prismatic, basal section with 4 or 8 sides and 2 cleavages at ~90º. Parallel extinction! In CPL, colors up to 1st order orange. ES(+), common zonation, rare twins. B(+/-), 2V from 58-86°.
Usually colorless or yellow, but may show weak pale green pleochroism. Monoclinic, high relief, without visible cleavage, in rounded or wedge-shaped grains. In XPL, intense 2nd and 3rd order colors. Parallel extinction, B(+), 2V = 6-19º. Black halos around it are possible. Very similar to zircon.
