106 
within themselves. Graphite has been deposited either 
at the junction of the igneous rock with its country rock, 
or in the included masses of limestone, or in the body of 
the igneous rock itself. Hence, the ore may be impregnated 
gneiss, impregnated limestone, or impregnated gabbro or 
pyroxenite. Itoccursin the form known as ‘“‘disseminated”’ 
graphite, but not as “vein or columnar’”’ graphite. 
The occurrence at the main pit is the most instructive. 
Here the ore occurs in a shoot of roughly lenticular cross- 
section, which sends offshoots or stringers into the sur- 
rounding rock. The whole ore-body occurs within a mass 
of gabbro, in which there are also “‘horses’’ of limestones, 
near which the graphite is more concentrated than 
elsewhere. 
The gabbro appears to be a normal type, except that 
it sometimes contains small quantities of quartz and of 
graphite. 
Both gabbro and ore are cut by ‘‘blue quartz veins,”’ 
which seem to be the latest products of the gabbro in- 
trusion. These veins are composed largely of quartz filled 
with minute inclusions, a variety of hornblende showing 
grass-green, drab and light yellow pleoch.oic tints being 
the only other mineral of importance. A little pyrite and 
graphite are the only other minerals present. The graphite 
is in part earlier than quartz, and in part later. 
A sample of ore from this pit proved to be a pyrox- 
enite composed mainly of grey augite. Brown, strongly 
pleochroic biotite is common; orthoclase, a smaller amount 
of plagioclase, titanite with strong reddish pleochroism, 
interstitial quartz, and a minute quantity of brown horn- 
blende are also present. Pyrite is older than the pyroxene, 
but graphite is one of the latest minerals to be formed. 
It occurs along the cleavage cracks of biotite, and at some 
points can be seen penetrating two adjacent grains of 
feldspar or of quartz. The presence of quartz in a pyrox- 
enite is another interesting feature. 
Other minerals associated with the graphite are apatite, 
in masses up to the size of a hen’s egg, pyrite, sometimes 
as veins of honeycomb or drusy nature cutting the ore, 
and molybdenite, of which a few flakes have been recog- 
nized. 
Some examples of the calcareous ore, from their ap- 
pearance in hand-specimen, indicate that the calcite, 
though probably derived from the limestone, was dissolved 
