MINERALOGY OF BLACK LAKE AREA. 
81 
KAOLIN. 
Kaolin occurs sparingly in some of the rocks, as an alteration product 
of the feldspar. 
Titano-Silicate. 
LEUCOXENE. 
The diabase which occurs in the area is, as a rule, very much altered, 
and leucoxene forms one of the secondary products usually present. 
Phosphate. 
APATITE. 
Specimens bearing well crystallized apatite were obtained about 5 
miles northwest of Black lake, near the road leading to St. Ferdinand 
de Halifax. They were not found in place, but in some boulders used 
in the construction of a stone fence, and their original location has not 
been traced. 
The first, and also the finest, specimens received by the writers, were 
collected in 1912 by D. A. Nicol, of the Geological Survey, whose attention 
was attracted to the boulders by some bright quartz crystals they con- 
tained. The quartz crystals in these boulders had been observed prior 
to this by Mr. A. Nadeau, of Black Lake, who, at the suggestion of 
R. Harvie, collected a number of specimens for the Geological Survey. 
The locality was later visited by one of the writers. 
The boulders, which are in many cases cavernous or drusy, consist 
mainly of massive white quartz, and have, doubtless, come from some 
quartz or pegmatitic veins in the immediate vicinity. A considerable 
amount of mica in small scales, more or less altered, is sometimes present, 
especially in the cavernous boulders, and, associated with it, are pyrite 
and siderite (page 24), both in small amount, together with their 
alteration product, a soft earthy limonite with which the druses are more 
or less filled. When this deposit is removed, the walls of the cavities 
are found to be lined with crystals of colourless quartz, usually small, 
but sometimes attaining a length of one centimetre ; these are described 
on page 15. Further inspection shows that many of the quartz crystals 
are superposed upon crystals of colourless, transparent apatite, which, in 
turn, rest on the massive white quartz, indicating that the apatite crystals 
are later than the massive quartz, but older than the quartz crystals. 
Owing to their manner of occurrence, it was not possible to remove 
any complete crystals of apatite from the specimens; nevertheless, a 
considerable amount of material was obtained, consisting of partially 
broken crystals, but eminently suitable for goniometric measurement. 
