46 The American Geologist. July, 1894 
Tin Crystalline Rocks. 
The descriptions already published in this series have given 
some of the features of the exhibits of the crystalline rocks, 
which might otherwise he mentioned here. The purpose of 
this note will he to supply some interesting facts that have 
not been noted 
One of the largest collections of the products of the crys- 
talline rocks was found in the exhibit of the Canadian Geo- 
logical survey. It was under the care of Dr. A. R. O Selwyn. 
aided by several of the officers of that survey. It embraced 
about L,500 specimens illustrative of the Archean. from Nova 
Scotia to the Pacific coast A unique feature here was a full 
series of all the forms of the world-famed Eozoon canadense, 
which are preserved by the survey to illustrate a historical 
episode in geological literature. 
Another interesting series consisted of serpentine, of vari- 
ous structures and colors, in many cases cut by asbestos veins, 
in others produced by change from Eozoon limestone. The 
former is from Thetford and the latter from Petite Nation. 
Dr. T. Sterry Hunt, in his discussion of the Canadian serpen- 
tines, divides them into two groups.* The older he consid- 
ered non-chroaaiferous, and the hitter carries much chromic 
iron. 
There was a very singular structure exhibited from the 
Little Rapids and High Rock phosphate mines, Portland. 
Quebec. Very many pyroxene masses, somewhat rounded, are 
embraced in a granite; and sometimes these dark masses so. 
penetrate the rock in sheets as to give it a stratified aspect. 
These appeared to be exactly like those dark masses so fre- 
quent in acid crystallines, which have been assigned some- 
times to '•concretionary*' forces. But this structure is in 
keeping with the idea that this rock was formerly a stratified 
conglomerate. 
Beautiful large slabs of white orthoclase containing garnets 
were exhibited from Buckingham, and apatite and mica in 
large crystals from the Lake Gerard mine, Wakefield. One 
mica crystal was thirty inches in diameter and eight inches 
thick. There were also tourmaline crystals six inches and 
*Geolo<r> of Canada, 1863, p. 608 c/ acq. 
