- Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases, is an opaque, impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. The common red color is due to iron(III) inclusions. Jasper breaks with a smooth surface and is used for ornamentation or as a gemstone. It can be highly polished and is used for items such as vases, seals, and snuff boxes. The specific gravity of jasper is typically 2.5 to 2.9. Jaspillite is a banded-iron-formation rock that often has distinctive bands of jasper.
- Chalcedony (Wikipedia)
Chalcedony (/kælˈsɛdəni/ kal-SED-ə-nee, or /ˈkælsəˌdoʊni/ KAL-sə-doh-nee) 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. Chalcedony’s standard chemical structure (based on the chemical structure of quartz) is SiO2 (silicon dioxide).