Chalcedony – (kal-sed-ne)
Chalcedony is similar to agate and jasper as a cryptocrystalline form of silica, composed of very fine quartz.
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 nearly black.
Chalcedony can occur in many varieties. Many semi-precious gemstones are forms of chalcedony. Some of the more notable varieties of chalcedony are:
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