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Prase

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PRASE.                                        185
It takes a polish which would be perfect if it was not resinous, and which it loses in the course of time. Its colour, quite different from that of the plasma, which is rather olive, is of a decidedly emerald green.
Small and rare are the pieces of pure prase, as this stone is always mixed and marked with lime, and its internal crystallization is not homogeneous or perfect. When it presents the appearance of a regular crystal it takes the form of a prism or pyramid, having six faces of medium size ; its external surface is rough and not very bright, but the breakage is scaly, concave, and of a vitreous light.
The prase in block is often formed of pieces stuck together, whose faces, somewhat rough, are obliquely lined.
This mineral, which has a specific gravity of 2*67, yields on being analysed
The ancients believed prase to be a kind of imperfect emerald, and besides the name of prasium, they also called it gmaragdoprasium ; but no one has left an exact description of it ; and Theophrastus, who suc­ceeded Aristotle, made greater confusion by giving the name of smaragdus to every kind of green stone. This
Porphyry Page of 243 Prase
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