www.mineralgallery.co.za Minerals F-J
Jasper
Name Jasper Chemistry SiO2 Uses As an ornamental stone Color Red brown or brown and even green Hardness 7 Specific gravity 2.5-2.8 Jasper is an opaque and fine-grained quartz. Colored red, yellow, brown, or off-white to gray by impurities, jasper has long been used as an ornamental stone because it takes a fine polish. The color of a streak made on a black jasper touchstone can determine with good accuracy the gold content of gold ores. It is the red variety of the cryptocrystaline group. The green variety which is flecked with red is known heliotrope or bloodstone and is fairly popular as a gemstone. The colouring is due to ferric oxide. Jasper is usually found in association with agate and chalcedony.

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