64 THE MINERALS OF TASMANIA. 



all exhibited the strong glow of incandescence which is 

 peculiar to the substance under radium emanations. Tra- 

 dition has it that many years ago a parcel of gem sand 

 from the Hellyer River was sent to England by the Van 

 Diemen's Land Company for expert examination, and in it 

 was found a single minute specimen of the diamond ; but 

 this has not been authenticated. It may be mentioned 

 that a presumably careful examination of Harvey's Creek, 

 from which two or three of the small specimens were 

 obtained, failed to reveal any of a larger size. 



106. DiASPORE (Hydrate of Aluwiniiim). 



This mineral crystallises in the orthorhombic system, 

 but is usually in the amorphous state. A substance having 

 the general physical characteristics of this species was 

 obtained by Mr. A. Montgomery, late Government Geolo- 

 gist, at the tip-head of that portion of the Bischoff Tin 

 Mine known as the Stanhope. 



107. DioPSiDE (Metasilicate of Calcium, Iron, and Mag- 



nesium). 



This is an almost white, to various shades of green, 

 variety of augite. It is at times quite translucent. It 

 occurs both massive and crystallised at the mine known as 

 the Tenth Legion, Comstock district. 



Analysis : — 



100-1 



Specific gravity, 3"23 ; hardness, about 6. (G. Waller: 

 " Report on the Iron and Zinc-lead Ore-deposits of the 

 Comstock District," Feb. 1, 1903— Mines Department.) 



108. Dolomite f Carbonate of Magnesium and Calcium). 



The pure crystallised form is of exceptional rarity, but 

 the ordinary massive kind is of common occurrence, and is 

 sometimes met with in considerable quantity. The gangue 

 of the silver-lead lodes of the Heazlewood and Dundas dis- 



