28 
DEPOSITS OF PHOSPHATE OF LIME. 
[BULL. 46. 
variable composition — a net-work of striated blades of triclinic feld- 
spar, brownish augite, black opaque grains of magnetite, and, commonly, 
small quantities of a green, chloritic mineral. 1 The quartzite is white, 
gray, or bloe. The blue variety often contains specks of felsite. 
These pyroxenes, feldspars, and quartzites are often mixed up in a per- 
fect net- work, very similar to that seen at Marblehead, Mass., and at 
Fig. 7. Section of apatite vein near Smith's mine, Oso, Frontenac County, Ontario, Canada. A,, 
country syenite; B, red and green apatite. Scale: 1 inch = 8 feet. 
many places in the metamorphic rocks of Mount Desert Island. Often 
whole hills are formed of these rocks, mixed in various proportions 
(Figs. 8 and 9). The gneiss in some places has no distinct line of sepa- 
ration from the pyroxene, but seems to have been impregnated with 
some of it, forming for a few feet from the line of contact a more or less 
pyroxenic gneiss, which is easily decayed and eroded by weathering 
(see Fi<r. 3). 
Fig. 8. Horizontal view of surface rock at Turner's Island, Clear Lake, Canada. A, feldspar; 
B, pyroxenite; C, hornblende; D, feldspar dykes; E, soil. Scale: 1 inch = 6 feet. 
In the Ontario district, as mentioned before, the pyroxene is often re- 
placed by hornblende. Thus at Bell's mine, in Frontenac County, little 
or no pyroxene is met with, and in its place large quantities of dark 
green hornb lende occur. The apatite here is found in a rock consisting 
1 B. J. Harrington : Geol. Survey Canada, Rept. Progress, 1377-78. 
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