^6 



THE MINERALS OF TASMANIA. 



diameter, but nearly 3 inches in length. Near the Great 

 Republic Tin Mine at Ben Lomond this mineral has been 

 discovered in execeptionally large and well-formed crystal 

 groups. The find occurred in surface-trenching across the 

 granite rock, when a somewhat large quantity of the beryl 

 was exposed, intimately associated with extremely large 

 and fine crystals of orthoclase. Many of the individual 

 crystals of the beryl measured fully 10 inches in length 

 and nearly 2 inches in thickness. The colour is unusual, 

 being a mottled yellow-brown, with a dull lustre on the 

 exterior surface. Many of the groups were strangely 

 united and semi-mackled, but all had the characteristic 

 hexagonal form. An approximate analysis kindly made by 

 Mr. W. F. Ward, Government Analyst, gave the following 

 return, viz. : — 



Per cent. 

 Silica = 66-0 



Glncina (Beryllia) = 8-0 



Alumina = 18-0 



Oxide of iron =: 8 



100 



Thin sections of this mineral from the lastmentioned 

 locality, when examined under the high powers of the 

 microscope, were found to contain numerous fluid 

 enclosures (liquid carbonic acid), varying very much in 

 size, but usually of an ovate form. They are commonly 

 arranged in lines, with a slight curvature, and graduate in 

 size from moderate dimensions to extremely minute. In 

 these enclosures minute bubbles are very plentiful, and 

 many have a spontaneo. i motion of variable intensity. 

 At the Shepherd and Marphy Mine, Bell Mount, specimens 

 have occurred several inches in length, wholly changed to 

 gilbertite, fluor, and chlorite. At the same locality small 

 slender crystals have been met with of a pale-green colour, 

 intermixed with quartz, topaz, molybdenite, and cassiterite. 

 The crystals are commonly embedded in a thin film of 

 pyrite. In a tin-bearing vein traversing the granite on the 

 St. Paul's River, opposite Brookstead, small bright-green 

 specimens have been obtained closely intermixed with 

 crystals of cassiterite. 



45. BiNDHEiMiTE (Hydrous Antimoimt e of Lead). 



Commonly known on the Western mining-field as 

 "' canary " and " picos " ore. It often occurs in somewhat 



