408 On the Chemical Composition of Phosphatic Minerals 
Composition of Two Caego-Samples of Silukian Phosphate. 
Vn 
1 
Jn 0. ^. 
4 
89 
3-21 
1 Q 
io 
O/ 
26 
37 
26-52 
Oxides of iron and alumina, fluorine, carbonic l 
26 
06 
29-65 
24 
01 
27-48 
100 
00 
100-00 
40 
7a 
28-68 
Mineral phosphates containing not more than the percentage 
of phosphate of lime which I found in these cargoes, and so 
large a proportion of oxide of iron and alumina, are hardly 
saleable in this country, and other samples which passed through 
my hands I found still poorer in quality. 
Immense quantities of phosphatic shale unquestionably exist 
in North Wales ; but the attempts to raise this mineral, I believe, 
have not hitherto been successful commercially, either to indi- 
viduals, or to limited liability companies which have been formed 
for the purpose of exploring the mines. 
5. Canadian Phosphate. 
Canadian phosphate is a variety of apatite which occurs in 
more or less distinct crystalline masses, or in crystals of a light 
green colour. It is found in large quantities in Canada, and 
occurs in fissures of granitic rocks, generally associated with 
gneiss or mica-slate. Usually it reaches this country in hard 
and heavy pieces, A'arying in size, and weighing from | lb. 
to 3 lb. and upwards. Occasionally perfect crystals in the 
shape of six-sided prisms may be picked out from cargoes of 
Canadian apatite. These crystals have a light green colour, 
and glass-like lustre and brittle texture. In this pure state the 
mineral is a definite compound of phosphate of lime and fluoride 
of calcium. The commercial article, in addition to these con- 
stituents, contains a little oxide of iron, which imparts to it 
generally a light green and sometimes a reddish tint, and more 
or less of the rock in the fissures of which it is found. The 
shiny blades of mica, which generally are mixed up with 
Canadian apatite, give it a glistening appearance. Good car- 
goes of Canadian phosphate contain on an average from 70 to 
