THE MINERALS OF TASMANIA. 81 



Although obscure in appearance and diminutive in size, 

 they are difficult of interpretation, and offer a field of in- 

 vestigation worthy of any student of natural phenomena. 

 That they are extra-terrestrial is almost beyond doubt; in 

 any case, it is obviously apparent that they can have no 

 connection with the known Tertiary volcanic rocks as occur- 

 ring here, for these are all of basic composition. The writer 

 is strongly of the opinion that but one shower of these ob- 

 jects occurred, in post^Pliocene times, which impinged upon 

 the earth in a north-western track, crudely extending from, 

 this Island to Victoria, from thence to the northern part of 

 West Australia, and thence to the western islands of the 

 Malay Archipelago. It has been noticed that examples col- 

 lected from many points along the track indicated have the 

 same general characteristics as regards form, colouration, 

 size, and composition. Moreover, they almost invariably 

 present the same amount of surface abrasion. Recent 

 writers have shown that there are reasonable grounds for 

 the supposition that they are of meteoric origin, but there 

 still exists a remarkable diversion of opinion as to their 

 source. 



In the sub-silicates we possess a few species which will 

 repay attention, not the least interesting being the water- 

 clear topaz, which occurs so abundantly al^out Mount 

 Cameron, at Bell Mount, and at Killikrankie Bay, Flinders 

 Island. These make veritable gem-stones of high lustre 

 and limpid beauty, and are often used as such. Sometimes 

 they are of unusually large size and good crystallogi-aphic 

 development. The variety pycnite occurs at Bischoff; in 

 patches of radiating disks. The ordinary black schorl, or, 

 more scientifically, tourmaline, is very abundant in large 

 masses and radiating bunches wherever the stanniferous 

 granite prevails. A hair-brown variety has been collected 

 near the northern flank of Mount Heemskirk, and its near 

 ally, zeuxite, which assumes an aciculated habit, is plentiful 

 at Mount Bischoff, its only locality in this Island. Our 

 local petrologists know how microscopically abundant and 

 disseminated sphene has proved to be. At the Lucy Riv^or, 

 a tributary of the Pieman, our only known sillimanite schist 

 occurs. In the zeolites, we have a goodly array of species, 

 in conformity with the variety and profusion of tiieir 

 parents, the effusive and other igneous rocks. Analcite is 

 often met with in the hauyne-phonolite of the Port Cygnet 

 series. The prevailing dolerite affords scolecite" whi.^h 

 affects a radiating structure. In the nephelinite of the 

 Shannon Tier the white natrolite is extremely plentiful, 

 freely bespattering the rock with bunches, and coating the 



