340 T. S. Hunt on Euphotide and Saussurite, 
is evident that feldspathic aggregates like those of Baste present 
a transition from the one to the other species of rock. ‘ 
by the frequent presence of quartz, w iabase the feld- 
spathic element is less silicious and decomposable by acids; (lab- 
radorite or a variety approaching anorthite) en however 
but secondary importance. e have seen that the orbicular 
diorite (or diabase) of Corsica contains a feldspar near anorthite 
in composition, while others in the Vosges, according to Deless, 
contain labradorite and andesine, the latter with quartz, Lory 
has described a diorite from the crystalline schists of the moul 
tains of Chalanches (Isére) which is made up of a chromiferous 
hornblende, with crystalline andesine and a pale greenish: el 
low epidote often intimately mixed with the feldspar, an¢® 
abundant as to characterize the rock. This epidote gave by 
cra silica 40°6, alumina 30-2, lime 17-7, protoxyd of 12 
‘2 = 99°7. 
. Diorites, as already mentioned, sometimes contain ae 
Associated with the Silurian ophiolites of Canada we often 
beds of rock which are mixtures of albite with hornblende 
pyroxene, sometimes with small portions of carbonates. fa 
diorites are tough, granular, sub-translucent, greenish or bh 
gray in color, weathering superficially to an opaque wie 
having a somewhat waxy lustre. Hardness 60; density 2 a 
2:76. The hornblendic element is sometimes nearly amo 
we fine grained variety of this diorite from Orford was 4 
ined ;.it had a somewhat yellowish-green éolor and a su”. 
par fracture. After ignition the — bi mk does 108 
ithout actiow 
iib sca ea be OOOO 5 ccs 63°40 
Alumina, 12°70 
oda, 7°95 
Potash, . 
BRT rs ee ire eam u be: Renee or 450 
ia, ; 3°37 
FrOuyS OF MO i. SIGs 4°23 
ignition, . “40 
99°68 
