A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...

THE GEOLOGICAL OCCURRENCE OF ANTIMONY ORES. 47
blende, steinniaimite, zinkenite, and cinnabar-ochre, rarely native
gold. Antimony salts of other metallic sulphides may also be found.
Antimony sulphide occurs in laminar crystals or in granular forms,
often massive, generally intermingled with quartz, thus forming a
compact mass occupying the whole vein. Stibnite-quartz ore might
be considered as an extreme development of silver or lead ore.
In 1851 S^narmont, in order to explain the formation of stibnite in
veins, made an experiment to obtain it by heating in a closed vase a
mixture of antimony and sulphur in the presence of pure water up
to 300°, or in the presence of bicarbonate of -soda at 250°. The contact
rocks are occasionally similar to those of veins containing lead
ore, rocks having white mica and green minerals. Hereafter this
type is denoted by A.
(a) Sub-Type : Antirnonial Gold-Quartz Veins. The stibnite is
itself gold-bearing, and accompanies other free gold-bearing gangues.
Hereafter this sub-type is denoted' by B.
2. Beds of epi-minerals, i.e. impregnated non-calcareous rocks. In
this case the antimony ore is impregnated in the rocks. Hereafter
this is denoted by C.
3. Epigenetic Stocks. The type is a metasomatic antimonial
deposit. Hereafter this type is denoted by D.
4. Bedded Deposits of antimony ore. The deposits are of sedimentary
origin. Some of the so-called bedded deposits may be due to the
impregnation of the country, i.e. of the neighbouring rocks. Hereafter
this is denoted by E.
In the following we shall take up the antimonial deposits of each
country in turn.
GERMANY.
Ores of antimony sometimes occur in the Devonian rocks of
Rhenish Prussia between Wintrop and Mentrop, four miles from
Arnsberg, where are found bands of bituminous limestone from
6 inches to 18 inches in thickness, interstratified between clay
wlates and siliceous shales. Stibnite penetrates all these strata,
which are overlain by Millstone Grit. It is-also noticed that the
stibnite accumulates more plentifully towards the middle part of
the various beds, but gradually thins out near the bedding planes of
deposition. Sometimes fragments of the "country" are included in
the more massive portions. (D.)
At the Hoffnung mine, near Briick, on the Ahr, the Devonian
graywacke slates have a N.-S. strike, with a dip of 45° towards the
west, cut through by N.-E. veins, dipping from 40° to 50° S. The