The schorl of the mineralogists of the last century united a
variety of substances which subsequent observations have separated
into several species. The green schorl is now the epidote, or the
Vesuvian, or the actynolite. The violet schorl, and the lenticular
schorl, are the axinite. The black volcanic schorl is the augite.
The white Vesuvian schorl is the sommite. The white grenatiform
is the leucite. The white prismatic is the pycnite, a species
of the topaz, and another is a variety of feldspar. Of the blue
schorl, one variety is the oxyd of titanium, another the sappare,
and another the phosphate of iron. The schorl cruciform is the
granatite. The octahedral schorl is the octahedrite, or anatase.
The red schorl of Hungary, and the purple of Madagascar, are
varieties of the oxyd of titanium. The spathique schorl is the
spodumen.
The black schorl, and the electric schorl, only remained, and to
avoid the confusion created by the use of the term schorl, the
name of tourmaline was given to this species by that celebrated
mineralogist, the Abbé Haüy.[50]
The tourmaline is found of almost every colour, and this variety
of colour caused at first a number to be formed into new species;
which are now considered only as varieties of the tourmaline: such
as the rubellite, the tourmaline apyre, and indicolite.
The different analyses of the tourmaline, however, affords a
greater variety of results than is known in almost any other
mineral.
The specific gravity of the black varies from 3.08 to 3.36
Green from 3.15 to 3.36
Red from 2.87 to 3.10
Analysis gives Silex from 35 to 58
Alumine 20 to 48
Magnesia 0 to 10
Iron 0 to 23
Manganese 0 to 13
Alkali 0 to 10
Water 0 to 4
These differences must be in some measure ascribed to a defect in
the accuracy of some of the analyses. But it appears that iron has
not been discovered in the red tourmaline. It is not unworthy of
notice, that the red tourmaline is considered as infusible, but the
others fusible.
The red tourmaline has been the most valued, from its scarcity,
its employment in jewelry, and the beauty of its crystals. It has
been discovered in Siberia, in Moravia, in the East-Indies, and
in Massachusetts. In Siberia it is found in a vein of decomposed
feldspar in a fine-grained granite, with black tourmaline. In
Moravia with quartz and lepidolite (or rose-coloured mica) in
gneiss. In the East-Indies, at Ava and Ceylon, but its geological
situation is not known, though it is probably in gneiss or granite.
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account