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RECORDS OF THE AUSTRALIAN MUSEUM. 



measure some fine specimens of crystallised Tasmanian minerals, 

 including topaz from Mt. Cameron, Flinders Island, and Bell 

 Mount. 



At Mt. Cameron topaz is abundant in the stanniferous drift, 

 but has not been found hi situ. It is usually much worn, but 

 some crystals well suited for crystal lographic determination were 

 sent to me by Mr. Petterd. Two crystals were determined on 

 the goniometer, one a crystal measuring 12 mm. x 13 mm. x 12 

 mm. and of a greenish colour shown in PI. xviii., fig. 3. It is fairly 

 rich in prism faces, having 7u (110), M (230), I ( I 20), and g (130) 

 present ; I predominates, but all are well marked faces and give 

 fairly good images. The terminal faces are rather dull ; only one 

 face of o (221) is present. The co-ordinate angles obtained are 

 given below. 



From another lot of small clear, colourless, crystals one was 

 selected and its faces determined (PI. xviii., fig. 4). It measures 

 7 mm. x5 mm. x5 mm., and in general habit resembles the last, 

 but has fewer prism faces and has the rather rare pyramid x 

 (243) fairly well developed but dull. The prism faces are striated 

 and give only fair signals. Appended are the mean co-ordinate 

 anyles found. 



