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Greek agate is a name given to pale white to tan colored agate found in the former Greek colony of Sicily as early as 400 BCE. The Greeks used it for making jewelry and beads. Brazilian agate is found as sizable geodes of layered nodules. These occur in brownish tones inter-layered with white and gray.
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO 4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO 2. Quartz is, therefore, classified structurally as a framework silicate mineral and ...
A microscopic picture of a fluid inclusion (non-permeable enhydro) showing a dark vapor bubble trapped in quartz. The term three phase relates to the three phases of matter, solid, liquid, and gas. This is a three phase inclusion in rock crystal quartz. The solid is a black material that is of bituminous origin.
Chalcedony. Chalcedony (/ kælˈsɛdəni / kal-SED-ə-nee, or / ˈkælsəˌdoʊni / KAL-sə-doh-nee) [2] is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. [3] These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic.
Chalcedony is a microfibrous quartz. [16] Agate is distinctly banded chalcedony with successive layers differing in color or value. [66] Onyx is a banded agate with layers in parallel lines, often black and white (sardonyx). [67] Magadi-type chert is a variety that forms from a sodium silicate precursor in highly alkaline lakes such as Lake ...
Hardstone carving, in art history and archaeology, is the artistic carving of semi-precious stones (and sometimes gemstones ), such as jade, rock crystal (clear quartz ), agate, onyx, jasper, serpentinite, or carnelian, and for objects made in this way. [ 1][ 2] Normally the objects are small, and the category overlaps with both jewellery and ...
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