140 The American Geologist September, i898 
Bayley has shown that the oHvine is a hyalosiderite with Mg: 
Fe about \\ to i. Small quantities of the rarer metals, man- 
ganese, cobalt, chromium and nickel also occur in this min- 
eral. 
Magnetite is scattered throughout the rock. Ordinarily 
it occurs in small grains usually having perfect crystal out- 
lines. Large irregular areas, making up a large part of the 
rock, are found in some sections. The proportion increases 
until the entire rock is composed of this mineral. Chemical 
examinations show that the mineral is sometimes free from 
titanium, but usually the latter constituent is present in vary- 
ing amounts up to 20 per cent. 
Apatite is present only in a small quantity. It occurs as 
small greenish to colorless crystals enclosed in the other 
minerals of the rock. 
Pyrite is common in some parts of the rock. It occurs in 
irregular aggregates sometimes an inch across and in thin 
sections it appears as small yellow cubes. It is commonly 
associated with the magnetite. 
Chalcopyrite appears as brass yellow grains or aggregates 
associated with the pyrite found in the magnetite deposits. 
The mineral is not abundant and seems to be developed only 
locally. 
Native copper occiu's as small strings or grains enclosed 
by the other minerals. Occasionally small grains of copper 
are imbedded in the clear plagioclase, and again fine threads 
of copper unite several plagioclase grains. Some hand speci- 
mens show copper up to five per cent of the whole mass. 
Graphite occurs as nodules and micaceous grains in the 
gabbro at its contact with the black slate member of the Ani- 
mikie. The mineral is derived from the carbonaceous ma- 
terial in the slate, and seldom is found far within the gabbro. 
It has a gray color. When wet the nodules may easily be cut 
with a knife, upon exposure to the air and when dr}- the 
graphite becomes hard and brittle. 
Garnets occur sparingly in small red grains near the con- 
tact wath the older rocks and near some of the magnetite de- 
posits. 
Hornblende is never found in the perfectly fresh rock. 
It is always associated with the diallafre and autjite. There 
