Glittering Stones >> Semi Precious Stones >> Chalcedony

Semi Precious Stone Chalcedony

Chalcedony is defined as a fibrous cryptocrystalline form of silica and composing a variety of mineral Quartz and moganite with a trigonal crystal structure. The chalcedony mineral has waxy luster and it may be semitransparent or translucent.

The varieties of chalcedony are agate, carnelian, chrysoprase, heliotrope and moss agate. The structure of Chalcedony was cryptocrystalline quartz and also composes of monoclinic polymorph of quartz called moganite. The Mohs scale hardness for the mineral is 6 to 7.5 with waxy luster. It is a more soluble mineral compared to quartz under low temperature condition, despite of its two mineral chemical identical. Wide range of colors are available in Chalcedony, but commonly seen colors are white to gray, grayish blue or shades of brown ranging from pale to nearby black.

Historical Facts of Chalcedony

Refractive Index	1.530 - 1.539
Chemical Composition	SiO2
Hardness	6 - 7
Density	2.59 - 2.61
Crystal Group	Hexagonal
Crystal system	Trigonal
Luster	Waxy, Vitreous, Dull, Greasy, Silky
Other names	Chalcedon, Calcedonia, Calcédoine
Varieties	Agate, Carnelian, Chrysoprase, Heliotrope, Moss agate
Color	White, Gray, Grayish blue, Brown, Pale black, Green, Blue, Lavender
Ocurrence	Brazil, Afghanistan, U.SA. Germany, India, Uruguay, Austarlia, Egypt, Italy, Scotland, South Africa, Namibia, Madagascar