Chalcedony - cryptocrystalline variety of quartz; kolomorfen. From the Greek. names of the ancient city of Chalcedon on the shores of the Marmara Sea, based megareytsami in VII. BC, an important trading center on the Bosporus.
Color: Gray macroscopic chalcedony, blue or brown, colorless in thin plates; variety Gemmological raznonasyschennye values are usually green, dirty green, yellow-green, yellow-orange, orange-red, red, brown, and multicolored. Often there are multi-colored inclusions.
Luster: greasy, waxy.
Hardness: 6.5-7.0 on the Mohs scale.
Density: 2,55-2,63 g / cc, the density of some specimens can reach 2.91 g / cc.
Cleavage: viscous material.
Optical properties: uniaxial mineral is optically positive.
Inclusions are numerous, both in crystalline quartz.
Occurrence: common in sedimentary rocks, which form continuous layers, in igneous rocks, which fills the voids and cracks, a secondary mineral of volcanic rocks. Occurrences are numerous. Colored varieties of Gemmological values chrysoprase - apple, grass-and emerald-green, heliotrope - dark green with red spots, carnelian - orange-red, sarder - brown, reddish-brown and red translucent, agate, onyx, sardonyx, are related chalcedony jasper, flint, prase, hornfels.
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