jasper

Jasper is an opaque type of silica that comes in a variety of colors, most commonly red, yellow, brown, green, and very rarely blue. It is made mostly of very fine-grained quartz or chalcedony, with other minerals contributing to its color and appearance. The common reddish color is due to iron 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, jewelry, seals, and snuff boxes. The density of jasper is typically 2.5 to 2.9 g/cm3. Jaspillite is a banded-iron-formation rock that often has distinctive bands of jasper.