APATITES OF CANADA. 
31 
thinks, that the erosive action in the veins has taken place in at least 
two different epochs. The appearance in the veins of drusy cavities 
and the parallel deposition of the different minerals observed in many 
veins are also arguments for the theory of concretionary structure. 
Professor Dawson thinks that many of the deposits of the Ontario dis- 
trict are true beds. 1 
Fig. 13. Horizontal section showing natural cavity in vein, Loughboro', Frontenac County, Ontario, 
Canada. A, country gneiss; B, apatite; C, pyroxene; D, calcite. Scale: 1 inch = 7 feet. 
Prof. B. J. Harrington 2 thinks that most of the phosphate deposits 
will come under the heading of fissure veins and pockets. He shows 
that many of the deposits cannot be beds, because they cut across the 
strata of the country rock. 
Many of the veins are of considerable length. A very continuous 
vein, composed of hornblende, calcite, and apatite, mixed in varying 
proportions and associated with sphene, zircon, mica, scapolite, etc., 
is found in Renfrew County, Ontario. This vein, or what may be a 
series of similar and parallel veins, was traced by the writer for a dis- 
tance of three miles, and it is said by the native prospectors to be trace- 
able for 27 miles. It, runs in a N. 40° E. direction, widening and contract- 
ing at intervals and varying from three to thirty feet in thickness. It 
can best be examined on Turner's Island, in Clear Lake, Renfrew County, 
Ontario, where several small openings have been made in it for the pur- 
pose of mining the rich apatite found there. 3 The island is three quar- 
ters of a mile long and from one hundred feet to a quarter of a mile 
wide. The vein runs through its longer axis from one end to the other. 
The apatite occurs in crystals, sometimes in considerable quantities 
and composing the greater part of the vein matter and at other times 
1 Quart. Jour. Geol. Soc. London, vol. 32, 187(5, p. 269. 
*Geol. Survey Canada, Rent. Progress lor 1877-'78-'79. 
3 Thesame or a similar vein is seen to great advantage on the land of Xavier 
Plaunf, on the south side of Clear Lake. It widens and eontracts at intervals and 
runs in the same general direction as the Turner's Island veiu. 
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