32 
DEPOSITS OF PHOSPHATE OF LIME. 
[BULL. 46. 
scattered sparingly through a mass of the crystalline minerals which 
accompany it. Apatite crystals of immense size have been found here- 
One prism is said to have weighed seven hundred pounds ; a crystal of 
zircon, almost a foot in diameter, is also said to have been found in the 
same vein. A crystal of sphene from this locality in the Harvard Min- 
eral Cabinet measures over a foot in length. The country rock on the 
island consistsof a confused mass of feldspar, coarse-grained, unstratified 
gneiss, and of a rock composed of feldspar and hornblende. Small quan- 
tities of green pyroxene are also found (see Fig. 8). The. vein is said to 
change into pure calcite at its extremities. It shows no signs, as far as 
seen, of banded or concretionary structure, but consists of a mass of 
crystallized minerals mixed in an apparently indiscriminate manner. 
Fig. 14. Northeast side of a pit in the North Star mine, Portland East, Ottawa County, Quebec, 
Canada. A, apatite; B, pyroxene; C, feldspar. Scale: 1 inch = 10 feet. 
Like most apatite deposits in Canada, the vein has no sharp line of di- 
vision from the country rock, but gradually blends into it. The horn- 
blende in the country rock becomes more perfectly crystalline and oc- 
curs in larger masses as the vein is approached, until fiually, when 
the vein is met, the hornblende and the feldspar crystallize out sepa- 
rately among the other minerals. " Such a blending of a vein with 
the walls," says Professor Dana, " is a natural result when its formation 
in a fissure takes place at a high temperature during the metamorphisin 
or crystallization of the containing rock." 1 This blending of the country 
rock with the vein matter does not, however, always happen, as sev- 
1 Dana's Mauual of Geology, 1875, p. 733. 
(50G) 
