Jasper is usually considered as chalcedony. Geologists sometimes put it in a group by itself within the quartz group because of its grainy structure. The name jasper is derived from the Greek word “iaspis, which means “spotted stone.” It incorporates various amounts of materials that give it both its opacity and color. Brick-red to brownish-red jasper contains hematite; clay gives rise to a yellowish-white or gray, and goethite produces brown or yellow. Jasper is formed through deposition from low-temperature, silicarich waters percolating through cracks and fissures in other rocks, incorporating a variety of materials in the process.
Jasper has been used for jewelry and ornamentation since Paleolithic times. The Babylonians believed that jasper influenced women’s diseases, and was a symbol of childbirth. The 11th-century Bishop of Rouen, Marbodius, stated that jasper “placed on the belly of a woman in childbirth, relieves her pangs.” This comes from a time when all stones were believed to be alive and have a sex, jasper being a female stone.
Uniformly colored jasper is rare; usually it is multicolored, striped, or flamed. Sometimes jasper can be grown together with agate or opal. There is also fossilized material. It occurs as fillings of crevices or fissures or in nodules.
It is used for ornamental objects, cabochons, and for stone mosaics.
There are many names of jasper used in the trade: Agate jasper (yellow, brown, or green blended, grown together with agate); Egyptian jasper (Nile pebble) strongly yellow and red; Banded jasper (layered structure with more or less wide bands); Basanite (fine-grained, black. It is used by jewelers and goldsmiths for streak-tests of precious metals); Blood jasper (name sometimes used for bloodstone); Hornstone (very fine grained, gray, brown-red, more rarely green or black. Sometimes hornstone is understood as a general synonym for jasper); Scenic jasper (brown marking, caused by iron oxide, resembling a landscape); Moukaite (pink to light red, cloudy. Found in Australia); Nunkirchner jasper (whitish gray, rarely yellow or brownish-red – named after deposits in Rhineland-Palatine), dyed with Berliner blue, misleadingly called “German lapis” or “Swiss lapis” in imitation of lapis lazuli; Plasma (dark green, sometimes with white or yellow spots; and Silex (yellow and brown-red spotted or striped).
Deposits of jasper are found in Egypt, Australia, Brazil, India, Canada, Kazakhstan, Madagascar, Russia, Uruguay, and the United States.