Diopside(redirected from Coccolite)
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a rock-forming mineral, a silicate of the group of monoclinic pyroxenes. Its chemical composition is CaMg[Si2O6]; part of the Mg can be replaced by Fe2+. Gray to grayish-green in color, it has a hardness on the mineralogical scale of 5.5-6 and a density of 3,270-3,400 kg/m3. Diopside is usually encountered as irregularly shaped grains with a good cleavage in gabbro, diabase, diorite, syenite, skarn, and other igneous and metamorphic rocks. More rarely it forms large transparent green crystals (so-called baikalite).