JASPER  , an opaque compact variety of

quartz, variously coloured and often containing argillaceous matter . The colours are usually red, brown, yellow or green, and are due to admixture with compounds of iron, either oxides or silicates . Although the term jasper is now restricted to opaque quartz it is certain that the ancient jaspis or iavais was a stone of considerable translucency . The jasper of antiquity was in many cases distinctly green, for it is often compared with the emerald and other green objects . Jasper is referred to in the Niebelungenlied as being clear and green . Probably the jasper of the ancients included stones which would now be classed as chalcedony, and the emerald-like jasper may have been akin to our chrysoprase . The Hebrew word yashefeh may have designated a green jasper (cf . Assyrian yashpu) . Professor Flinders Petrie has suggested that the odem, the first stone on the High Priest's breastplate, translated " sard," was a red jasper, whilst tarshish, the tenth stone, may have been a yellow jasper (Hastings's Dict . Bible, 1902) . Many varieties of jasper are recognized . Riband jasper is a form in which the colours are disposed in bands, as in the well-known ornamental stone from Siberia, which shows a regular alternation of dark red and green stripes .

Egyptian jasper is a brown jasper, occurring as nodules in the Lybian desert and in the Nile valley, and characterized by a zonal arrangement of light and dark shades of colour . Agate-jasper is a variety intermediate between true jasper and chalcedony . Basanite, lydite, or Lydian stone, is a velvet-black flinty jasper, used as a touchstone for testing the purity of precious metals by their streak . Porcelain jasper is a clay indurated by natural calcination . (F . W .