BY W. F. PETTERD. 69 
Mount Cameron they are abundant, although generally much 
worn; in thestanniferous drift large examples have been frequently 
met with. ‘They occur more or less abundantly all through the 
north-eastern Tin-producing districts, Thomas’s Plains, Moorina, 
and the Weld River being noted localities. The Topaz rarely, if ever, 
occurs on the West or North-western portion of the island, the only 
form of this substance, so far discovered, being the Topaz-porphyry 
of Mount Bischoff, which was first recognised and minutely 
described by the late Professor von Groddeck, of the celebrated 
School of Mines at Clausthal (Pro. Royal Soc. Tas., 1885), and 
the cylindrical variety Pycnite, which occurs disseminated in the 
more abundant Quartz-porphyry of the same locality. 
The Topaz-porphyry of Bischoff is usually more or less 
stanniferous, and is comparatively scarce—the ordinary rock being 
a Quartz-porphyry, which in general characteristics is allied to a 
form known as Eurite: it is granular to crystallized in structure, 
the combined Topaz being pseudomorphous after Quartz; the 
crystals are usually very minute, and strongly retain the well-known 
hexagonal form of the parent mineral, but with a milky and less 
lustrous appearance. The only other recorded locality for this 
peculiar and interesting form of Topaz-rock is the Tin mines of 
the Schneckenstein of Saxony. This restricted distribution, 
structure, and chemical composition, render it of extreme interest 
to the mineralogist. 
I am informed that smal] specimens of Topaz have been sparsely 
found in alluvial drift in the vicinity of Mount Claude, but the 
identification is open to doubt. 
232, VIVIANITE (Phosphate of Iron). 
In groups of crystals which are occasionally nearly half an inch 
length, from cleavage planes in rock, adit Mount Bischoff; in 
blue and green amorphous clay-like mass, Waratah River; in 
crystallized bunches, No. 1 North Pioneer reef, at Waterhouse ; 
as a soft clay more or less impregnated with the phosphate, Supply 
Creek ; of a dark blue colour in fibrous radiating bunches with 
granular Quartz, Lucy Creek, Pieman River; in large quantity 
disseminated in decomposing argillaceous shale, North Bischoff. 
233. VALENTINITE (?) (Oxide of Antimony). 
As small white crystals in lode-matter. Hay’s Prospecting 
Association mine, Castray River. | 
234, VAUQUELINITE (Chromate of Lead and Copper). 
This isa rare mineral, which hitherto has been considered 
peculiar to the Silver-lead mining districts of Siberia. The 
substance as occurring here has a peculiar and unusual siskin-green 
colour, and is found in an amorphous, somewhat mammillated mass 
of a dull appearance. Before the blowpipe and in Nitric Acid it 
