52 
They are found in many places amongst the crystalline rocks of this Colony, 
but are of little value without they are of good size and clear. 
Kaolinite. 
Kaolin, or China Clay , occurs in chalk-like masses, either compact, friable, or 
mealy, having often a microscopic crystalline structure. 
It is white when pure, but is also of many shades to dark reddish-brown, and 
is greasy to the touch, its hardness being 1 to 2*5, and specific gravity 2'4 to 2*6. 
It is a silicate of alumina combined with water when pure, but when impure con¬ 
tains iron. It is the result of decomposed felspar, and is infusible and insoluble 
in acids. Pure kaolin makes the fine porcelains, the impure forms earthenware, 
pipe clay, &c. 
Mica or Muscovite. 
It is always found crystalline, the crystals of which split into plates and scales, 
varying in colour from a white to green, yellow, and brown, with a pearly lustre. It 
is transparent, or translucent, tough and elastic, with a hardness of 2*5, specific 
gravity of 2*7, with a composition of silica 46*3, alumina 36*8, potash 9*2, oxide of 
iron 4*5, fluoric acid 0*7, and water 1*8. 
Mica is mostly found in nature as a constituent of granitic and other meta- 
morphic and igneous rocks. When it attains sufficient size to be of commercial 
value, it occurs associated generally with quartz and feldspar as a granite-dyke, in 
which the crystals of the different minerals are of such great size that it loses all 
the character of a rock, presenting more the appearance of a lode. 
The portions where the mica is of sufficient size to be worth working, occur in 
bunches or patches, often of considerable extent, along the dyke, but it is a matter 
of uncertainty whether it will continue of the size in depth. 
The surface mica is generally stained by coatings of iron and manganese 
between the thin plates. This, of course, reduces the value considerably, but 
should the mica continue in depth, it will be found to be quite solid and clear 
when taken from below the reach of the atmospheric action, or below the water 
level. Mica can he worked by blasting, being hand-dressed afterwards, as from 
its elastic nature it will stand more knocking about than the harder and more 
brittle minerals, which would be shattered. For export it has to be trimmed up 
square, and all waste and damaged mineral removed, so that the blocks are ready 
for splitting on their arrival, and the freight is saved on refuse. Its value depends 
on size, clearness, and the ease with which it splits. 
It occurs in this Colony near Bunbury, Bindoon, the Gascoyne, and on the 
Pilbarra and Kimberley goldfields, but has not yet been found in large enough 
plates to pay to work. 
Topaz. 
The Topaz is of a pale yellow, white, green, blue, or reddish colour, transparent 
to translucent, occurring always in the "crystalline state, haring a hardness of 8, 
specific gravity of 3*5, and a composition of silica 16*2, silicon fluoride 28*1, alumina 
55*7. It is easily distinguished from tourmaline, quartz, and other minerals, by its 
brilliancy and hardness. No topazes are known to have been found in this Colony 
up to the present. 
Carbon. 
Symbol , C.; atom ic weight, 12; specific gravity , 3 5. 
Carbon is one of the elements most commonly met with in nature, as besides 
occurring in the crystalline form as the diamond and graphite, it also 5 enters into 
combination with other elements to form all organic substances. 
