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CHRYSOPRASE. 71
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It
is generally transparent and sometimes opaque, of little brightness
although it takes a good polish. Its cleavage is united and resinous.
Its hardness is somewhat less than that of the calcedony. It is
coloured by nickel, and when subjected to a great heat it loses its
tint.
It
is found in small veins or lines of about fifteen millimetres in
thickness, interrupted by a green earth containing nickel. Its
analysis presents
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Its specific weight is 2*5.
The
mineralogical strata of the Chrysoprase are immediately under the
vegetable earth, at two or three feet depth ; sometimes it is procured
in the clefts of the rocks, inclosed in a kind of asbestos. It is full
of deep cavities, like the malachite.
They
Chrysoprase, unlike all other gems, is only found in Europe, and even
there in but one country, that of Prussia, in the province of Silesia,
in a part of the country called Kosemiith, situated on the mountain of
Glasendorf, and at Stachlan, near Cologne ; and for this reason it is
commonly called " Prussian grey." As it always presents chinks
intermingled with grains, it is not easy to understand the union of its
heterogeneous parts.
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