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:

Agate

Carnelian

Chrysoprase

Moss Agate

 

For more information about Chalcedony try these links:

http://stoneplus.cst.cmich.edu/chalcedony.htm

http://www.mindat.org/min-960.html

http://minerals.usgs.gov/minerals/pubs/commodity/gemstones/sp14-95/chalcedony.html

http://www.minerals.net/mineral/chalcedony.aspx