Berkite —silicilied 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 chalce Ionic base, with much green delessite (chlorite) and red spots of iron oxide.
Jasper—opaque ; dull red, dull green, and ochre yellow.
Milky quart-—opalescent or milky, yellowish by transmitted light.
Onyx—bands or strata of white, grey, black ; translucent to opaque.
Plasma—very translucent ; rich leaf green.
Porrelant jasper—sub-translucent; often white and pink.
Prase—translucent, but spotted ; muddy olive green.
Piband jasper—opaque bands, dull red and dull green ; sometimes yellow.
Pock crystal—transparent and colourless.
Rose quartz —transiilcent and pale pink.
Sapphiric 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,
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