Jasper, an
aggregate of
microgranular quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...
and/or
cryptocrystalline
Cryptocrystalline is a rock microstructure, rock texture made up of such minute crystals that its crystalline nature is only vaguely revealed even microscopically in thin section by transmitted polarized light. Among the sedimentary rocks, chert a ...
chalcedony
Chalcedony ( or ) 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 ...
and other mineral phases,
is an
opaque
Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light. In radiative transfer, it describes the absorption and scattering of radiation in a medium, such as a plasma, dielectric, shie ...
, impure variety of
silica
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...
, usually red, yellow, brown or green in color; and rarely blue. The common red color is due to
iron(III)
In chemistry, iron(III) or ''ferric'' refers to the element iron in its +3 oxidation state. ''Ferric chloride'' is an alternative name for iron(III) chloride (). The adjective ''ferrous'' is used instead for iron(II) salts, containing the catio ...
inclusions. Jasper breaks with a smooth surface and is used for ornamentation or as a
gemstone
A gemstone (also called a fine gem, jewel, precious stone, semiprecious stone, or simply gem) is a piece of mineral crystal which, when cut or polished, is used to make jewellery, jewelry or other adornments. Certain Rock (geology), rocks (such ...
. It can be highly polished and is used for items such as vases,
seals, and
snuff boxes. The
density
Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...
of jasper is typically 2.5 to 2.9 g/cm
3.
Jaspillite is a
banded-iron-formation rock that often has distinctive bands of jasper.
Etymology and history

The name means "spotted or speckled stone," and is derived via
Old French
Old French (, , ; ) was the language spoken in most of the northern half of France approximately between the late 8th (variant of
Anglo-Norman ''jaspe'') and
Anglo-Norman language">Anglo-Norman ''jaspe'') and Latin (nom. ) from Greek language">Greek
Greek may refer to:
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group
*Greek language, a branch of the Indo-European language family
**Proto-Greek language, the assumed last common ancestor of all kno ...
''iaspis'' (feminine noun), from an
Afroasiatic language
The Afroasiatic languages (also known as Afro-Asiatic, Afrasian, Hamito-Semitic, or Semito-Hamitic) are a language family (or "phylum") of about 400 languages spoken predominantly in West Asia, North Africa, the Horn of Africa, and parts of the ...
(cf.
Hebrew
Hebrew (; ''ʿÎbrit'') is a Northwest Semitic languages, Northwest Semitic language within the Afroasiatic languages, Afroasiatic language family. A regional dialect of the Canaanite languages, it was natively spoken by the Israelites and ...
).
Green jasper was used to make bow drill">:fa:یشم">یَشم).
Green jasper was used to make
, Persian, Hebrew, Assyrian, Greek and Latin. On Minoan civilization, Minoan Crete, jasper was carved to produce seals circa 1800 BC, as evidenced by archaeological recoveries at the palace of Knossos.
Although the term jasper is now restricted to opaque quartz, the ancient ''iaspis'' was a stone of considerable translucency including
.