22 
MR, J. T. HOTBLACK ON PRECIOUS STONES. 
in Ceylon is the sapphire d’eau, it is white with celestial blue, 
a sort of mixed colour when looked at in different directions, 
a peculiarity due to its dichroism. 
Garnet. 
This is, perhaps, the most abundant and most largely used 
of all the “ precious ” stones, and is consequently of but small 
value. It varies very much, ranging in hardness from 6.5 to 7.5, 
in S.G. frqm 3.0 to 
composition : — 
4.3, and I 
have 
notes of 
the followin. 
Alumina ... 
19.35 
28.50 
20.50 
21.20 
Silica 
38.25 
40.00 
36.30 
31.80 
Lime 
31.75 
3.50 
— 
37.20 
Oxide of Iron 
7.33 
16.50 
43.20 
6.00 
Magnesia 
2.40 
10.00 
— 
3.00 
It is, as a rule, only called garnet by jewellers when dark red ; 
when bright red it is called by them almandine ; when vermilion 
it is called pyrope ; when white, yellow, or orange it is called 
cinnamon stone ; when red and cut en carbochun, or tallow-topped, 
it is the carbuncle, but most jewellers, at all events in the provinces, 
seem not to know this. 
Garnets are also found in brown, green, black, and in fact of any 
and every colour, but these are very little used in jewellery. This 
stone is found in its different varieties almost everywhere in the 
igneous rocks, and among other pebbles derived from the igneous 
rocks, it is found with almost all the other precious stones, 
very many in the Diamond Mines at Kimberley. 
The Chrysolite 
has a hardness of C.O to 7.0, S.G. of 3.3 to 3.5, and I find its 
composition stated as silica 39.73, magnesia 50.13, proto-oxide 
of iron 9.19. 
This is the true chrysolite, though the jewellers generally call 
the chrysoberyl by that name. 
When yellow, red, brown, or light green it should be called 
chrysolite, when dark olive green it is the peridot, and when 
yellowish green it is called olivine. This stone is met with in 
many places in substance of volcanic origin, it has been found in 
the lava of Vesuvius, and is like all the harder crystals, no doubt, 
