Jasper

Jasper is an opaque silica rock made of very fine-grained quartz and chalcedony. It is most often red, yellow, brown or green, and its common red colour comes from iron oxide. It breaks with a smooth surface and takes a very good polish, which is why seals, vases and jewellery have been made from it for thousands of years. Sources describe jasper sometimes as a variety of chert (the flint-type rock) and sometimes as a rock containing chalcedony.

Ornamental stone and jewellery: it takes an excellent polish, so vases, jewellery, seals and snuff boxes are made from it. Touchstone: black jasper was used to test the purity of gold and silver alloys. The colour of the streak an alloy leaves when rubbed on the stone shows its gold content. History: jasper was a favourite stone of the ancient world; its name can be traced in Arabic, Persian, Hebrew, Assyrian, Greek and Latin.

It has a hardness of 6.5–7 on the Mohs scale. It scratches glass and steel; a steel knife cannot scratch it. Its specific gravity is 2.5–2.9 g/cm³.

Its best-known localities: Sicily, Italy; Purbalingga district, Central Java, Indonesia; Biggs area, Oregon, USA; Bruneau River canyon, Idaho, USA; Ynys Llanddwyn, Wales.

Known localities in Türkiye: Tokat, Türkiye.

It is completely opaque; no light passes even through thin edges, which is the easiest way to tell it from translucent chalcedony. Its hardness is 6.5–7: it scratches glass, and a steel knife cannot scratch it. It breaks with a smooth surface; a broken face looks dull, but it shines when polished. Basanite (Lydian stone, touchstone): one of the names used for black, jasper-like stones; one kind is a black variety of jasper, the other a black volcanic rock close to basalt. It was used as a touchstone for testing the purity of gold and silver alloys.

On the “street to diamond” value ladder it sits on step 5 of nine: Ornamental stone. The value of jasper depends on the vividness of its colour and the beauty of its pattern, on whether it is free of cracks and cavities, and on the quality of its polish. It is generally a plentiful, inexpensive ornamental stone; “picture jaspers”, whose cut faces show picture-like patterns, and coloured kinds tied to particular deposits are more sought after. Trade names such as “ocean” or “forest fire” usually describe a place or a look and do not name a separate kind of stone.

According to Lithica, a fourth-century author, the gods were believed to answer the prayers of whoever wore polished grass-green jasper with rain; Damigeron adds that the stone served this purpose only if properly consecrated. In the same period jasper was believed to drive away evil spirits and to protect the wearer from the bites of venomous creatures; a German author of the 11th or 12th century recommends laying the stone on a snake bite. In Türkiye, some news and crystal-therapy sites claim that jasper protects against the evil eye and other bad influences, symbolises honesty and helps control outbursts of anger. The same sources also claim that jasper eases blood circulation, strengthens the immune system and helps with stomach and liver complaints. There is no scientific evidence that jasper brings rain, drives away evil spirits, draws out venom, or improves blood circulation, immunity, the stomach or the liver. George F. Kunz traces the snake-bite belief to the idea that the stone draws the poison into itself. A snake bite needs immediate medical help, not a stone; stomach, liver and heart-and-vessel problems need a doctor’s supervision. This section reports beliefs; it is not health information. There is no scientific evidence for these claims and no stone replaces medical treatment.