Sard and sardonyx, translucent, light to dark brown varieties of the silica mineral chalcedony, historically two of the most widely used semiprecious stones. Sard and its close relative carnelian have been used in engraved jewelry for centuries.
Chalcedony is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic. Chalcedony39;s standard chemical structure is SiO2. Chalcedony has a waxy luster, and may be semitransparent or translucent. It can assume a wide range of colors, but those most commonly seen are white to gray, grayish blue or a shade of brown ranging from pale to n
General Sugilite Information. Chemical Formula: KNa2 2Li3Si12O30. Composition: Molecular Weight = 1,041.66 gm. Potassium 3.04 % K 3.66 % K 2 O. Sodium 1.83 % Na 2.47 % Na 2 O. Lithium 1.41 % Li 3.04 % Li 2 O. Titanium 0.28 % Ti 0.46 % TiO 2.
Sardonyx Geological Properties This stone combines alternating layers of sard and onyx; hence its name. Sard appears anywhere from a dark orange to red to almost black. Onyx, although thought by most to only appear in black, can appear in almost any color. These two types of the mineral chalcedony are paired in bands to create sardonyx.
It is cryptocrystalline, consisting of fine intergrowths of the silica minerals quartz and moganite. Its bands are parallel to one another, as opposed to the more chaotic banding that often occurs in agates. Sardonyx is a variant in which the colored bands are sard rather than black. Black onyx is perhaps the most famous variety, but is not as common as onyx with colored bands.
Science amp; Origin of Sardonyx. Sardonyx is the name given to a variety of Onyx that contains bands of Carnelian. It was first recorded back in 1837 by J.D. Dana and named after the Ancient Greek city and capital of Lydia, Sardis. The original word sard was also used to describe very dark colored Carnelian up until modern times.
Formula: SiO2. A variety of Agate. A variety of Agate with reddish brown and either black or white bands. Visit gemdat for gemological information about Sardonyx.
Sardonyx. A variety of Agate with parallel bands of white contrasting with the brownish red body colour. Layered sardonyx stones are an ideal medium for the art of cameo, intaglio and relief carving. General Information. A variety or type of: Agate, which is a variety of Chalcedony, which is a variety of Quartz. Chemical Formula. SiO.
June 10, 2020
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