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QUARTZ
101

Beekite—silicified corals, shells, or limestone, resembling chalcedony.

Bloodstone—translucent to opaque; green with red spots.

Cairngorm—transparent and smoke grey, yellow or brown.

Cat's-eye—translucent grey or greenish, with chatoyancy.

Chalcedony—cloudy or translucent; white, yellow, brown, blue.

Chrysoprase—translucent; pale bluish green.

Cornelian—translucent, like horn; yellow, brown, red.

Egyptian jasper—opaque, concentric, and other layers of yellow, brown, or black.

Heliotrope—a chalcedonic base, with much green delessite (chlorite) and red spots of iron oxide.

Jasper—opaque; dull red, dull green, and ochre yellow.

Milky quartz—opalescent or milky, yellowish by transmitted light.

Onyx—bands or strata of white, grey, black; translucent to opaque.

Plasma—very translucent; rich leaf green.

Porcelain jasper—sub-translucent; often white and pink.

Prase—translucent, but spotted; muddy olive green.

Riband jasper—opaque bands, dull red and dull green; sometimes yellow.

Rock crystal—transparent and colourless.

Rose quartz—transulcent and pale pink.

Sapphirine quartz—translucent and pale greyish blue.

Sard—very translucent; red, brownish red, crimson, blood red, blackish red, golden, amber.

Sardonyx—a stratified stone, having one or more strata of sard.

Smoky quartz—transparent; of various hues of grey and brown.

But this list by no means exhausts the varieties of quartz, for of agate alone we have fortification agate, moss agate, and mocha stone, eye agate, and brecciated agate. All of these stones, and indeed the majority of those in the list just given, so far as their colours and markings are natural and not due to artificial treatment, consist of amorphous or crystalline silica, variously arranged or disposed, and associated with colouring oxides and silicates containing oxides of iron, manganese, or nickel. The claim of very few of these varieties of quartz to the rank of precious stones can be sustained. It is not merely that they are abundant, but their brilliancy and beauty are not sufficiently pronounced to entitle them to high rank amongst stones for jewels. The great merit of the artistic work executed in these materials, in Greek, Roman, and cinque-cento times has indeed ennobled the sard, the onyx, the prase,