296 MINERALS OF TASMANIA. 
dd. COAL, 
River Don; Mersey; Port Arthur; Seymour; Schouten 
Island ; South Cape; near Waterhouse; Three Hut Point; New 
Town; York Plains; Jerusalem; Cullenswood; Mount Nicholas; 
Sandfly ; Adventure Bay; Port Cygnet; Hamilton; Richmond ; 
Prosser’s River; Spring Bay; Mt. Munro; Fingal; Longford; 
Jericho; Inglis River; Mersey River; Western Bluff; Gad’s 
Hill; Magnet Range. 
Full detailed descriptions of our Coal measures, with numerous 
analyses of samples, will be found in the Proceedings of the Royal 
Society ot Tasmania, 1851, Johnston’s Geology of Tasmania, 1888, 
and in the Tasmanian Official Record, 1892. 
78. DOLOMITE (Carbonate of Magnesia and Lime). 
The pure crystallized 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 districts is often composed 
of an irregular mixture of Brown-spar, Siderite, Calcite, with a 
limited quantity of quartz most of which is more or less stained 
with the oxides of Chrome and Nickel. At Dundas a blue~ 
coloured variety has been obtained associated with Galena. 
The massive form occurs at Mount Claude, near Mount Pelion, 
Heazlewood, and Dundas. 
79. DIAMOND (Pure Carbon). 
The occurrence of the Diamond in this island is extremely 
doubtful. It has been reported that a single minute specimen was 
detected in a parcel of gem-sand that was obtained in the vicinity 
of the Hellyer River, and sent to England for examination by the 
Van Diemen’s Land Company many years ago. 
80. DIALOGITE (Carbonate of Manganese). 
See RHODOCHROSITE. 
81. DUFRENOSITE (Sulph-arsenide of Lead with Copper 
and Silver). 
Usual colour steel-grey, with a reddish-brown streak and metallic 
appearance. It is said to occur intermixed with Tetrahedrite and 
Cupriferous Pyrites at the Fahl Ore mine, Dundas. 
82. DUNDASITE (Hydrous Carbono-phosphate of Lead and 
Alumina). 
This apparently new mineral compound forms an incrustation 
on ferro-manganese gossan. It is composed of small spherical 
ageregates, usually closely matted together. Under the lens these 
bunches show an extremely fine radiating structure. The colour 
internally is silky milk-white with a velvety outer crust of a 
dusty yellow-brown, 
