20 MINERALS OF TASMANIA. 
water; Maria Island; Mersey River; Mackintosh River } 
Gordon River; Don; Heazlewood; Beaconsfield; and other 
places. 
As Travertine, at Geilston; as Roestone, on the west side of 
the Savage River; as Iceland Spar, near St. Mary’s and near 
Deloraine; abundant, stalactitic, at Chudleigh and near Frank- 
ford ; in more or less perfectly crystallized bunches and bands in 
lode-matter at Heazlewood, Zeehan, and Dundas; in vughs and 
imbedded in basalt rock, Bischoff and Lefroy ; of a pink colour 
with carbonaceous matter, Swansea; as small blue-coloured 
crystals, Madam Melba Mine, Dundas; flesh-coloured in 
Syenite Porphyry composed of Orthoclase, Hornblende, and 
Quartz in a felspathic magma. (Ballarat School of Mines 
Museum.) 
66. COBALTINE (Arsenide of Cobalt and Iron). 
Occurs in masses with cupriferous pyrites, galena, and grey 
copper, Penguin Silver Mine, Penguin River. (James Smith.) 
67. CASSITERITE ( Oxide of Tin). 
As is well known, this is the only commercial ore of Tin. It 
crystallizes in the pyramidal system ; in habit it affects short four- 
faced prisms with complex terminations ; it often occurs mackled, 
and is, when freshly broken out, of adamantine lustre. As a 
distinguishing character the streak or powder is always pale-brown 
‘or greyish white. In colour this mineral varies in a great degree ; 
it occurs commonly black and in various shades of brown, but is 
often almost colourless, red, yellow—pale and dark, white, grey, 
and sometimes variegated. In structure it may be compact, fibrous, 
nodular, radiated, or crystalline. According to colour or structure 
its varied forms are termed by miners black tin, resin, amber, ruby, 
wood, shot-holed, blistered mahogany, and other local appellations. 
Alluvial tin is generally much water-worn or rolled, but in many 
cases the crystals are but little abraded; it is usually opaque, but 
is occasionally translucent to almost clear transparent. It is well 
known to metallurgists that stream or alluvial tin—as with gold— 
is richer than that derived from its matrix or lodes; the reason for 
this, some mineralogists suppose, is that the alluvial mineral has a 
kind of growth by continuous coatings received from the metal held 
in solution; but it appears to me more reasonable to suppose that 
this peculiar feature is caused by the outer crust being abraded, 
leaving a richer central portion or nucleus. Cassiterite occurs in 
either the eruptive granite rock itself or in the immediate neighbour- 
hood. The rock itselfis,as a rule, comparatively poor in Felsparand 
shows a corresponding increase in the important mineral Mica, 
which invariably contains more or less Lithia as a constituent, so 
that the presence of this element may be looked upon as a fair 
indication of the existence of Tin Oxide. The mineral is 
