22 MINERALS OF TASMANIA. 
River a massive variety occurs which is known as “ White Tin;” it 
is an amorphous compact ore of a dull white to pale brown colour. 
At Mount Ramsay a peculiar variety has been obtained sparingly 
intermixed with the normal kind; it is a small angulated form of 
a brown colour and highly polished, generally but little water- 
worn. That from Constable’s Creek is of a rich brown-colour, 
with striations of various shades in fine crystallized masses of 
considerable size embedded in a quartz gangue. The highly 
polished crystals and mackles from the Blue Tier and vicinity 
are exceptionally fine, and samples from some of the mines in the 
Ben Lomand district are remarkable for the same reason. 
The ore from the Iris River, near the Middlesex Plain, is, as 
a rule, a very minute black to dark brown polished form, which 
often occurs dispersed throughout a white kaolinic clay or 
decomposed felspar. The Bischoff Tin is dark brown to black ; 
the major portion of that obtained is found in small granular 
particles, but very large masses of almost pure Cassiterite have 
been obtained mainly composed of solid aggregations of crystals. 
At this locality this mineral has been obtained intimately associated 
and scattered throughout various forms of Pyrites, mainly” 
arsenical, and it is reasonable to suppose that the greater portion 
of the lode mass or “ Bonanza” that has been worked had its origin 
from a huge mass of Pyrites afterwards transmuted to Limonite, 
and now forms the well-known Brown Face ofthe mine. The recent 
discovery of Native Sulphur associated with a mass of fine quartz 
Sinter or Geyserite, showing a close resemblance to samples from 
the Hot Springs of New Zealand, may as investigation proceeds 
throw some light upon the important subject of its origin. The 
principal rock formation at Mount Bischoff is Quartz-porphyry— 
often containing small crystals of Pycnite—with shoots of the 
Topaz-porphyry, but tin is often found in the clefts of the adjacent 
killas or metamorphic slate. At north-east Dundas Cassitterite 
is also reported to occur, mixed with various forms of pyrites, in 
some respects resembling the Bischoff formation. 
It is said that Resin and Ruby tin occur at the base of the 
Norfolk Range, north of the Pieman River, and that the general 
character of the tin-bearing drift much resembles that of the north- 
eastern fields, but this requires confirmation. 
The principal stanniferous rocks of this island are Granite, 
Quartz and other Porphyry, Greissen, and Protogine. Quartz 
is not an unusual lode gangue, and kaolinic clay and Limonite 
form secondary matrices. The principal associated minerals are 
Wolfram, Pyrites of various kinds, Molybdenite, Tourmaline, 
and more rarely Fluor-spar, Chlorite, and Bismuth. 
The stanniferous drift is mainly composed of fragments and 
crystals of quartz and other rock débris, that of the North-east 
coast containing numerous water-worn Sapphires, Zircon, 
Pleonaste, Menaccanite, and rarely Gold, Beryl, and silicified 
