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PRECIOUS STONES 153
Massive Varieties of Quartz
Agate...............Ribbon agate has strata of different
colors
playing into each other. Circular agate has stripes of different
colors arranged around the centre. Eye agate has points of other colors
within
the centre. Fortification agate has angular colored bands suggesting a
plan of fortress. Moss agate contains green or brown mineral matter
(oxide of iron) having an appearance of vegetable growth. The colors
may be darkened by boiling the stone in oil and then dropping it in
sulphuric acid.
Asteriated Star......Is a quartz containing^ substances between layers of crystal, which, cut en cabochon across prisms, exhibits asterism.
Aventurine Quartz . . Is gray, brown, or reddish brown,
translucent, and contains iridescent spangles of mica or other mineral.
Basanite............A velvet-black, flinty jasper used for
trying metals; called also Lydian stone and touchstone.
Beckite .............Silicified corals, shells, or limestone,
resembling chalcedony.
Bloodstone..........Heliotrope. Deep green chalcedony,
colored with red spots (oxide of iron).
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