50 
Before the blowpipe it remains unaltered, both alone and with soda, and this 
and its hardness, which is next to a diamond, distinguishes it from any other 
mineral. Bright, clear crystals of a blue colour are called sapphires, the red ones 
rubies, the opaque and translucent are called corundum, whilst the earth or where 
tine particles are intermixed with much oxide of iron it is called emery. 
The clear varieties are of great value as goins, for owing to this hardness they 
retain their polish, sharp face, and their brilliancy for a long time. 
Calcium. 
Symbol , Ca.; atomic weight, 39-9; specific gravity , 158. 
Compounds of this element are very abundant and widely distributed over 
the earth crust as carbonates, sulphates, and phosphates; but it is never found 
in the metallic state, in which form it resembles gold in colour, and like that 
metal it is very ductile and malleable; it gradually tarnishes in dry air, and 
quickly in moist. 
It decomposes water, forming a hydrate and liberating hydrogen. It is 
readily dissolved by dilute nitric acid, but. strong has no effect upon it. 
Carbonates . — It occurs most commonly in nature as a carbonate, the pure form 
of which is called calcite, calc spar, dog-tooth spar, Iceland spar, satin spar, and 
stalactites ; but the more earthy varieties, as chalk, limestone, marble, are of the 
greater economic value for building stones, lime, and cement, some of the latter 
varieties containing a large percentage of clay and iron, which, when burnt, often 
possess the power of setting under water, when they are called hydraulic. Calcite 
and stalactites occur in the caves on the Moore and Hill rivers, also between the Yasse 
and the Leeuwin. The limestone at Albany, all along the coast in patches from 
the Leeuwin to the N.W. Cape, at Gingin, Yatlieroo, Daudaragan, the Irwin 
River, near Geraldton and Northampton, all the way North from the Gascoyne 
to the tableland at the head of the DeGrey, the Kimberley District, and there are 
also many surface deposits in the interior. 
Sulphates.— In. tliis form it is called gypsum, and occurs all over the salt lake 
areas of the interior, as well as being associated with the carboniferous formation 
wherever it outcrops. 
This mineral, when burnt., forms plaster of Paris. 
Phosphates.—No crystalline phosphates have yet been discovered but it forms 
one of the most important constituents of guano, which is met with and worked on 
many of the islands around this coast. 
NON-METALLIC' MINERALS. 
THEIR OCCURRENCE AND USE. 
Silicon. 
Symbol, Si.; atomic weight, 28. 
is never found free h 1 
quartz, flint, chalcedony, opal 
111 / itil H 1 n .1 it 1 
rocks; it is also found k 
the ashes of wheat and grass. 
