194 THE MINERALS OF TASMANIA. 



niferous granite abutting on to amphibolite ; and at Bell 

 Mount, Middlesex. In short, it is extremely rare to find 

 tin ore unaccompanied by this mineral. Green tourmaline, 

 or zeuxite, is a local form, which at Mt. Bischoff is 

 extremely abundant, and practically constitutes a rock- 

 mass in portions of the mine. The crystals are small, and 

 so interwoven as to partake of the nature of a felted mass. 

 The crystals rarely exceed an inch in length, being com- 

 monly quite minute. They sometimes form fine tufted 

 masses of radiating acicular crystals in small cavities. It 

 varies at the Bischoff to a greyish-blue colour, but the 

 green is the most abundant. The finest development of 

 this variety occurs at the Stanley River, at which locality 

 the individual crystals are often larger than those so 

 abundant at Bischoff, and the colour is more intense. It 

 also occurs sparingly at one or two places on Mt. Heems- 

 kirk, and at all localities it appears to accompany tin 

 ore. Brown tourmaline occurs in somewhat small prisms 

 arranged as radiating bunches in a quartz matrix at Mt. 

 Ramsay; while at Glenora, near the Gap at Mt. Heems- 

 kirk, it occurs rather abundantly of a distinct dull hair- 

 brown colour. The common black form is also known 

 under the Cornish vernacular name of " schorl." Pseudo- 

 morphs of the green-coloured variety after orthocla&e are 

 fairly common at the Stanley River, and also occasion- 

 ally occur at Mt. Bischoff. The light greyish-blue, dense, 

 and more massive tourmaline of Mt. Bischoff was analysed 

 by Dr. H. Sommerlad in the laboratory of the Royal 

 Mining Academy of Glausthal, Hartz, with the following 

 results: — Silica, 26*86; alumina, 36*72; boron trioxide, 

 10-56; iron protoxide, 5*66; manganese protoxide, 0-66; 

 lime, 0*34; magnesia, 3-92; potassa. Ml; soda, 3*57; 

 water, 1-16; fluorine, 0-61; total, 101-17. Spec, grav., 

 3-042. At Mt. Ramsay this " schorl " variety occurs as 

 long, intensely black prisms, of the characteristic form, 

 penetrating and embedded in solid white quartz. The 

 individual prisms are at times up to nearly 3 inches in 

 length and well formed. 



" One of the most noteworthy occurrences of tourmaline 

 in Tasmania is that which is developed in the granite of 

 Mt. Heemskirk. The normal granite has a reddish hue, 

 and contains areas in which the colour is notably paler. 

 The latter variety is characterised by the presence of an 

 enormous number of spheroidal nodules composed of 

 quartz and tourmaline, the majority of which range in 

 diameter from 2 to 5 inches. They prove more resistant 



