JASPER, an impure variety of quartz. It is compact, and being very hard it takes a fine polish. It occurs in many colours— dark green, brown, yellow and sometimes blue or black. Occa sionally it is found banded with many different coloured stripes. Unlike chalcedony, it is opaque, and does not possess a splintery fracture. The term jasper is now restricted to opaque stones, but the ancient jaspis or iciarcs was at least partially translucent, and probably included some chalcedony and chrysoprase. Many medic inal values were attributed by the ancients to this stone, and even in 1609 it was still believed that a jasper hung about the neck strengthened the stomach.
Egyptian jasper is brown, occurring as nodules of an agate-like formation in the Lybian desert and the Nile valley. Red jasper is
found at Hessen, Lohlbach and Dakota. In riband jasper the colours are arranged in bands, as in the well known Siberian stones, in which there is a definite alternation of red and green stripes. Agate jasper is intermediate between true jasper and chalcedony. An artificially coloured jasper is extensively produced in imitation of lapis lazuli.