14 
MUSEUM BULLETIN NO. 27. 
are seen to be perfectly transparent and beautifully crystallized; the 
most common form is that of the simple octahedron; many of them, 
though, are apparently combinations of the cube and octahedron. The 
hardness could not be determined with accuracy owing to the very small 
amount of material available for experiment, but in the course of their 
removal from a beaker with the aid of a camel’s hair brush, it was noted 
that even such light pressure as was occasioned in this way was sufficient 
to cause abundant fine scratches upon the glass. When exposed to 
radium emanations they can be seen to fluoresce distinctly, a test which 
is regarded as conclusive evidence of the character of the mineral. 
"No. 2. From the same locality as the preceding specimen. A dull 
greenish grey serpentine. Treated in the same manner as No. 1, it gave 
negative results. 
"No. 3. From the same locality as No. 1. A bright pink vesuvianite. 
It likewise gave negative results. 
"No. 4. From near Black Lake station. A dull grey peridotite. 
It also gave negative results.” 
When examined with a high power under the binocular microscope, 
the crystals are found to have, in most cases, an octahedral habit, and 
they frequently exhibit a parallel growth in the direction of one of the 
crystal axes, as shown in Figure 2, which represents a typical crystal 
enlarged nearly one thousand diameters. 
Sulphides. 
MOLYBDENITE. 
Dresser 1 mentions the occurrence of molybdenite in very small 
amount at the Caribou pit; he states that the mineral was found in vein- 
lets, enclosed in vesuvianite. 
The writers have collected a few specimens carrying molybdenite 
both from the Caribou pit and also from the American chrome pit. In 
each case the mineral is disseminated through a garnetiferous aplite 
in the form of minute flakes. These are seen especially near the contact 
between the aplite and the serpentine, and occasionally also encrusting 
the serpentine as a film at the immediate contact. The molybdenite, 
however, is by no means abundant, and was observed in a few specimens 
only. 
A microphotograph of a thin section of the aplite from the Caribou 
pit is shown in Plate IX and the rock is described under garnet on 
page 50. One flake of molybdenite in this rock had a diameter of 
one centimetre, but otherwise, both at this locality and also at the 
» Ibid, p. 84. 
