Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases,^[1][2] is an opaque,^[3] 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 density of jasper is typically 2.5 to 2.9 g/cm³.^[4] Jaspillite is a banded-iron-formation rock that often has distinctive bands of jasper.

The name means "spotted or speckled stone," and is derived via Old French jaspre (variant of Anglo-Norman jaspe) and Latin iaspidem (nom. iaspis) from Greek ἴασπις iaspis (feminine noun),^[6] from an Afroasiatic language (cf. Hebrew ישפה yashpeh, Akkadian yashupu).^[7] This Semitic etymology is believed to be unrelated to that of the English given name Jasper, which is of Persian origin,^[8][a] though the Persian word for the mineral jasper is also yashp (یَشم).