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Chalcedony |
Chalcedony is a microcrystalline form of quartz. In a broad sense can describe all varieties of microcrystalline quartz, which are many, jasper, agates, carnelian, chrysoprase, bloodstone, onyx, etc.. In a restricted sense the name chalcedony is applied to the blue variety in shades. In this sense we refer here.
The name comes from an ancient city in Asia Minor (now Turkey): khalkedon, It occurs in geodes, stalactites, kidney-shaped masses. It is always porous (can be dyed easily.) It is very compact, fibrous and has a high resistance to abrasion and carving.
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| COLOR | AZUL en diferentes tonos | TRANSPARENCIA | Traslucida |
| RAYA | Blanca | I.R. | 1,530 - 1.540 |
| DUREZA | 6 1/2 - 7 | Br | 0.004 - 0.009 |
| DENSIDAD | 2.58 - 2.64 | DISPERSION | No |
| EXFOLIACION | Ausente | PLEOCROISMO | No |
| FRACTURA | Concava irregular | ABSORCION | No |
| S. CRISTALINO | Agregados fibrosos | FLUORESCENCIA | No |
| FORMULA QUIMICA | SiO2 | BRILLO | Mate, cereo. |
The chalcedony has been a highly prized gem and precious stone since ancient times. In every culture of antiquity is present in all possible forms, postage, cabochons, beads, small sculptures and so on. It is very durable, so we have got many pieces old. Currently are made of chalcedony cabochons, beads, cameos and carvings
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| The current reserves are many, the most prominent are in Turkey, Namibia, Mexico, USA, India, Madagascar, Brazil In the Iberian Peninsula is in Fraga (Zaragoza), Barcelona, Murcia, Almeria. |
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