, an aggregate
of microgranular quartz
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
. 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 items such as vases, seals
, and snuff boxes
. The specific gravity
of jasper is typically 2.5 to 2.9.
A green variety with red spots, known as heliotrope (bloodstone)
, is one of the traditional birthstones
for March. Jaspilite is a banded iron formation
rock that often has distinctive bands of jasper.