776 A. P. COLEMAN 
It is rather curious that pyrite and not pyrrhotite is found in the 
older norite, which comes closer to the European nickel-bearing norites 
than the Sudbury nickel eruptive in chemical composition. 
Granite.—Varieties of granite, and granitoid gneiss occur in bands 
along the southern nickel range or at no great distance from it, and 
are probably connected with the nickel eruptive in origin, repre- 
senting a very acid phase in contrast with the very basic norite referred 
to above. The granites, which should not be confounded with the 
much older granite and gneiss of the Laurentian, are of two kinds, 
one coarse-grained and porphyritic, the other medium-grained; and 
apparently of two ages, the coarser variety being generally older than 
the nickel eruptive, while the finer-grained variety is distinctly 
younger, since it sometimes penetrates the norite as dikes or irregu- 
larly shaped bodies. ‘The oldest of these granites is later in age than 
the basic norite, since it has carried off masses of it or of greenstones 
formed from it. 
These acid rocks are normal granites with much quartz and 
microcline, some microperthite and orthoclase, a little oligoclase, 
a small amount of biotite, and still less muscovite. No micropeg- 
matite has been found in thin sections of these rocks, a point of con- 
trast with the granite of the acid edge of the nickel eruptive. ‘These 
granites may have been split off from the general hearth by magmatic 
segregation without stoping or absorption of more acid materials. 
An analysis of one of the later, finer-grained granites by Mr. 
James Horton gives the following results: 
SiO ie Real he ae a Meee ae We ae aa 7 Cen 2 
ALSO sira\ ie feces oie ged eos ee ed ee EO? 
Be, Og te Ve Re a a ee ee ey 
EQ si OF Re tee ee secant ame eat 2 
AS BUN ©) eae Sar a oc ete acca Mer ame A Ate Sar 1r2 
Mig Que tis Lee iether deanna erent 26 
CaQieoGr sa. Games, cic Eee 0 mie: 58 
K.0 ee eam me Mak oe ean RODS Ne Let Abie 10) 
ING OP ois aaa oe eo a eae) eee SO SEAT 
fs © aR Areas et SUNG Bh okie gk Sas oe 16 
1 © ie came maa a TE es eal CON ae Oe es MN .10 
Ota as ha NGF eee OS ae ae Ratee aeeee eee COAT O 
Specilic gravity: lager 2s oc. yma sry tora tea 25 C) 
