16 
MUSEUM BULLETIN NO. 27. 
are little more than striations or lines. The measured and calculated 
angles for these forms are as follows: 
Form 
G» 
9 
P 
Measured 
Calculated 
Measured 
Calculated 
+ l 1 
27° 03' 
26° 59' 
67° 38' 
67° 35' 
+ y i 
24 09 
24 00 
69 48 
69 42 
+ 1 1 
20 31 
20 38 
72 15 
72 14 
+ YI 
17 56 
17 59 
74 59 
74 26 
As these indices are calculated from single measurements only, the 
forms are not to be regarded as firmly established. 
MAGNETITE. 
Magnetite occurs as a primary constituent of the basic igneous 
rocks, and also in the form of small irregular masses and veinlets within 
the massive serpentine, or associated with the chrysotile; it is also 
found intergrown with the chromite. 
In one interesting occurrence, nodules of magnetite up to 1 * S cm. 
in diameter are completely enclosed within chrysotile, in such a way that 
the specimens have the appearance of a knotted string. However, when 
the chrysotile is stripped from the magnetite, the surface of the latter is 
found to bear the impressions of the asbestos fibres, indicating that in 
this instance the magnetite may have been formed later than the chry- 
sotile. 
CHROMITE. 
Deposits of chromite of workable size have been found at many points 
in the neighbourhood of Black lake, most of the productive mines being 
situated along the great serpentine ridge, which attains a height of 900 
feet above the track of the Quebec Central railway; the locations of the 
more important pits are shown in Figure 1, page 5. 
Occurrence. 
The chromite does not occur in well-defined crystal individuals, 
but forms fine granular aggregates or apparently compact masses, 
having a black or slightly brownish-black colour, pitchy sub-metallic 
lustre, and brown streak. The compact ore often has a plates tructure, 
breaking along ill-defined planes of parting, which, in some cases, are 
coated with a thin film of a white flaky biaxial mineral, which is probably 
clinochlore. The surface of the ore along such partings may also be 
highly polished or slickerisided, due to differential movement or faulting 
subsequent to its solidification. 
