18 MINERALS OF TASMANIA. 
gem-stones of the highly natural Oriental colouration are of 
exceptional occurrence. A limited number of very fine stones 
have been obtained which, after passing through the lapidary’s 
hands, have been pronounced by good authorities to be gem stones 
of considerable value and quite equal to the average of those from 
Ceylon. They are usually very much waterworn, although 
occasionally specimens are met with that clearly show the 
rhombohedral crystallization. The Oriental Amethyst and Ruby 
are not known to occur in this island, but occasionally an Oriental 
Topaz has been obtained in Main Creek, near Thomas’s Plains. 
The colour varies through all shades of blue, green, and purple, 
and from translucent to opaque. They aresometimes parti-coloured, 
showing various shades of blue and yellow to colourless. The 
highly-valued asteriated variety has been obtained, but it is of 
extreme rarity. A fine large example of the ordinary translucent 
Sapphire was obtained in the Weld River weighing 264 carats, 
but the colour was not of even shade or that so highly valued. 
Mount Cameron; Thomas’s Plains; Weld River; Main Creek ; 
Moorina ; Branxho!m ; occurs opaque, colourless to dirty blue and 
erey, Blyth River ; in clear blue fragments at the Boat Harbour, 
near Table Cape. 
The Sapphire has not been discovered 7 situ, although its 
matrix will in all probability be found to be Granite. 
60. COPIAPITE (Yellow Sulphate of Iron). 
Occurs in small quantity, resulting from the decomposition of 
Melanterite, in one of the adit levels at Mt. Bischoff. This 
mineral is often observed on Melanterite as a thin incrusting 
powder; it is probably a transmutation of that species by loss 
of water. Some pyrites from Bischoff decompose directly to this 
mineral—this peculiarity is especially noticeable in cabinet 
specimens, which after a time are often literally transformed into 
the mineral. This pyrite is found in a lode composed of 
Sphalerite, Fluor-Spar, and Steatite, east of the great mine. 
61. CHABAZITE (Hydrated Silicate of Alumina, §.) 
An abundant zeolite, which occurs in the cavities of amygdaloidai 
Basalts. The obtuse rhombohedral crystals are usually well formed, 
clear, and colourless. Abundantnearthe railway bridge that crosses 
the Hellyer River; of small size but well formed groupings, Spring- 
field; associated with other zeolitic minerals, Olivine, and 
Calcite, Sheffield and near Mt. Claude ; with ferro-calcite, Lefroy ; 
occurs abundantly in vesicular basalt at Mt. Pelion and vicinity,— 
the crystals are well developed and in fine groupings, often lining 
the cavities. Rounded waterworn nodules of the black basalt are 
often met with in the streams which clearly show the implanted 
crystal groups, and are sometimes mixed with other species of 
zoelitic minerals and ferro-calcite. 
