There
are mines of alabastrite at Volterra, in Italy, and at Lagny, in
France. It yields easily to the lathe, the file, the scalpel, and the
graving-tool; and -very generally in Italy ornaments for common use are
made of it under the name of Volterra chalk, and sold at a very low
price. It receives a fine polish, although not equal to that of marble.
When formed into a hollow globe, and reduced to a substance of extreme
thinness, it acquires such transparency as to allow light to pass very
pleasantly; which, when transmitted through it, is more vapoury than
that which passes through ground glass. Although generally white,
sometimes it has a veining similar to that of the Oriental alabaster.
It
is easy to distinguish alabastrite from alabaster; it is less
resistant, and can even be scraped by the nail; and being dissolved in
acetic acid, gas is not disengaged, as is the case with alabaster,
which is afterwards always of a colour tending to yellow. Besides, this
latter is formed of a carbonate of lime harder than that sulphate which
composes alabastrite.
Alabaster
is found in stalactites and stalagmites in the caves of calcareous
districts; and is there formed by the filtration of water loaded with
carbonate of lime, often mixed with colouring substances, such as
metallic oxides.
The
large masses of alabaster are produced from closely crowded
stalactites, in which fresh filtrations of similar substance have
filled the vacant spaces; and consequently stripes and various
undulations are visible in their interior.
