Rocks, Minerals & Ores
Mineral Sequence in the Cady Mountains
Chalcedony (var. Jasper)
SiO2Cady Mountains, Mojave Desert, CA
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Mineral Sequence in the Cady Mountains
Chalcedony (var. Jasper)
Tectosilicates; a variety of quartz (silicon dioxide), often with some iron and aluminum
Color and Luster: clear red to brownish red(Var. carnelian and sard, carnelian and sard in layers (Var. onyx), bright green with spots of red(Var. heliotrope and bloodstone), variegated(Var. agate), banded, agate with moss- or tree- like inclusions(Var. moss agate), apple-green(Var. chrysoprase), variegated and mottled red, yello, and brown(Var. jasper), whitish, dull gray, smoky brown to black(Var. flint), also white to gray, brown, blue, and black; waxy luster, vitreous, dull; streak white
Hardness:7
Cleavage: None
Fracture: Conchoidal, brittle to tough
Crystals: None; chalcedony is a microcrystalline variety of quartz usually occuring as crusts with botyroidal or mammillary forms; or compact, banded
The Audubon Society Field Guide to North American Rocks and Minerals
