Peridot

Peridot: a magnesium and iron silicate (Mg,Fe)2(SiO4); end of the Olivine series (Forsterite-Fayalite); it crystallizes in the rhombic system in striated prims or in corroded granules, green yellow color; green colored specimens generally have a 12-15% Iron content; the presence of traces of Chromium generate more vivid hues; density 3.30-3.40; Mohs Hardness 6.5-7; R.I.: 1.640-1.655, 1.657-1.673, 1.675-1.690; these values are variable due to iron and magnesium contents.

Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]
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