226 T. S. Hunt on the Chemical and Mineralogical relations, etc. 
older metamorphic rocks in Canada. The so-called granites of 
the Laurentian and Lower Silurian appear to be in ever 
indigenous rocks; that is to say, strata altered in situ, and still 
retaining evidences of stratification. The same thing is true 
with regard to the ophiolites and the anorthosites of both series ; 
in all of which the general absence of great masses of unstrat- 
ified rock is especially noticeable. No evidences of the hypoth- 
etical granitic substratum are met with in the Laurentian system, 
although this is, in one district, penetrated by great masses of — 
syenite, orthophyre, and dolerite. Granitic veins, with minerals 
ese, g 
having formed, like metalliferous veins, by aqueous deposition 
in fissures in nthe strata. 
‘The al 
whether they are susceptible of a general application. I have 
found that the blue akong labradorite of the Labrador series 
of Canada is exactly represented by specimens from Scarvig, in 
Skye; and the ophiolites of reins resemble those of the Lauren- 
tian series in Canada. Many of the rocks of Donegal appear to 
me lithologically identical with those of the Laurentian period; _ 
while the serpentines of Aghadoey, containing chrome and 
onegal cannot be distinguished from those which characterize 
the altered Paleozoic strata of Canada. It is to be rem ’ 
that chrome- and nickel-bearing serperitines are met with in the 
same geological horizon in Canada and Norway; and that those 
of the Scottish Highlands, which contain the same elements, a 
Roderick Murchison, would be of similar age. The serpentines 
of Cornwall, the Vosg ges, Mount Rosa, and many other aioe - 
agree in containing chrome and nickel; which, on the other 
seem to be absent from the serpentines of the primitive gneiss- 
formation of Scandinavia. It remains to be determined rat far 
chemical and mineralogical differences, such as those which 
been here indicated, are geological constants. Meanwhile, ree 
greatly to be desired that fature eae end mineral 
vestigations of crystalline rocks should be made with this ques 
-tion in view; and that the mater strata of the Britisa 
Isles, and the more modern ones of southern and central Europ 
be ied _ with 1 reference to the, a = — it 
lay before th 
"Montreal, Catiacdey Tas 28; 1863, 
