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HAÜYNA.
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very rare, and the few that are to be met with belong most certainly to the Greco-Romano school.
Likenesses of the Persian kings belonging to the Sassanidse dynasty may be often seen engraved on these gems.
Nothing
is more easy than to recognise an antique intaglio on garnet ; because,
being ver}' brittle, the greater number of them found are broken or in
fragments. Besides, time confers on them a softness of colour which
defies imitation by even the ablest artists.
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XLVII.
HAUYNA.
From the
illustrious Abbé Haiiy, one of the most eminent mineralogists, this
stone takes the name which, in compliment to him, was given it by
Monticelli.
It
was first discovered by Gismondi, who, having met it associated with
mica and green pirosene, on Mounts Laziali, called it, hence, Lazialue.
Afterwards,
Monticelli found it on Vesuvius. The hauyna, then, is a substance
composed of alumina, silex, potash, protoxide of iron, sulphuric acid
and soda, and of which, according to the celebrated Luigi Ceselli, the
exact analysis is as follows :
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