68 MINERALS OF TASMANIA. 
crystals which are of a yellow colour, coating the clefts of lode 
material. Hampshire Silver mine, Hampshire Hills. 
230. TALC (Hydrated Silicate of Magnesia). 
A beautiful snow-white form occurs in the Arthur River near 
its Junction with the Hellyer ; on the west branch of the Clayton 
Rivulet this mineral occurs as a vein of a yellowish-white colour, 
and is about two feet in width; about one mile north of Remine, 
on the coast, a beautiful semi-transparent form exists in considerable 
abundance ; it abuts upon the Serpentine outcrop; it varies in 
colour from translucent white to aclear pale green; alarge formation 
occurs on the Meredith Range, near the Castray River: it is 
massive, compact in structure, and very pure ; the prevailing colour 
is a beautiful pale sea-green, shining, and extremely unctuous ; of 
sub-crystalline structure in large masses, Magnet Range; in 
radiating masses with Cassiterite, North Valley, as well as impure 
and massive at other places at or near Mount Bischoff; Asbestos 
Mountain, near Beaconsfield ; near the Parson’s Hood Mountain ; 
Ben Lomond; Blue Tier. 
231. TOPAZ (a Fluo-silicate of Alumina). 
When waterworn this mineral has much the appearance of the 
more common mineral Quartz, from which it may be known by its 
greater hardness and rhombic crystallization. 
It occurs in this island in pale shades of green and blue to colourless 
—the yellow, Saxon, and the Brazilian forms are unknown. It is 
obtained at several localities in profusion, of the “finest water, and 
of a brilliancy scarcely inferior to that of the Diamond” (Bristow, 
“Glossary of Mineralogy,” 1861, p. 383). 
This beautifully brilliant gemstone is unfortunately out of 
fashion for the jeweller’s art, although fifty years ago it was much 
in vogue. It is found of all sizes; specimens have been obtained 
measuring nearly eight inches in length and of perfect transparency. 
At Killicrankie Bay, on the west side of Flinders’ Island, it occurs 
in great profusion both as waterworn pebbles and more rarely in 
fine well-defined crystal forms in alluvial drift resulting from the 
detritus of the Granite rock: several other minerals are common 
with it, including Quartz, Zircon, and Tourmaline. The Topaz is 
but rarely obtained in situ,—it usually occurs in vughs in the Granite 
associated with crystals of Felspar and Quartz. Gould states 
(Pro. Royal Soc. Tas., 1871, p. 60), that they originate from 
bands varying in width from one to several feet, composed of the 
ordinary ternary Granite minerals highly magnified, the size of 
the individual minerals being “enormously increased so that the 
blocks of Felspar, Quartz, and even mica, occur up to several feet 
in dimension. These appear to be the scene of the most abundant 
source of the Topazes, which have crystallized out into natural 
cavities from whence they have been delivered by erosion.” At 
