Jasper, an aggregate of microgranular quartz and/or chalcedony and other mineral phases, is an opaque, impure variety of silica, usually red, yellow, brown, green and blue in color. The common red color is due to iron inclusions. The mineral aggregate breaks with a smooth surface and is used for ornamentation or as a gemstone. It can be highly polished and is used for jewelry, vases, seals, and snuff boxes.
The specific gravity of jasper is typically 2.5 to 2.9.
Jasper is around a 7 on the Mohs Hardness Scale.