APPENDIX. 533 



Geognoslic Position. — It is a rolled mass. An opinion of the 

 specific character of the rock may be dubious, from the smallness 

 of the specimen. It appears to have been detached from a stra- 

 tum of gneiss, and is essentially composed of quartz. The black- 

 ish color of some parts of this latter mineral would, at first glance, 

 lead us to attribute this color to the presence of hornblende ; but, 

 on closer examination, it will be perceived to be owing to a dark- 

 colored steatite, which, in certain parts of the rock, is well de- 

 veloped, soft, and easily cut. A little calcspar is iDtermingled 

 with the steatite. 



Locality. — I am indebted to the politeness of Lieut. Lewis S. 

 Johnston, of the British Indian Department, at Maiden (U. C), 

 for the opportunity of adding this specimen to the mineralogical 

 cabinet of the Lyceum. This gentleman, as he informed me, ob- 

 tained it from an Indian, who picked it up on the southeastern 

 shores of Lake Huron, near Point aux Barques, in Michigan 

 Territory, That part of Lake Huron was cursorily examined by 

 me, in the year 1820, in the course of the expedition conducted 

 by Gov. Cass, through the upper lakes, &c. I consider it re- 

 markable, even in a region abounding in rolled rocks, for the 

 great number and variety of granite, gneiss, hornblende, and trap 

 boulders, scattered along the shores of the lake. The water here 

 is generally shallow and dangerous to approach in vessels ; these 

 boulder stones sometimes extending and presenting themselves 

 above water for a mile or more from land. But we could not 

 satisfy ourselves by an examination necessarily partial, that either 

 of the primitive species mentioned, existed there in any other 

 condition than as rolled masses, or displacements of rock strata, 

 contiguous, perhaps, but not observed. Dr. Bigsby has informed 

 me, that he observed the gneiss in situ, on the northwestern shores 

 of this lake. The nearest rock in place, and that which in fact 

 constitutes the abraded and caverned promontory of Point aux 

 Barques, is gray sandstone. 



The occurrence of this metal in the copper-bearing and other 

 metalliferous rocks of this region, may be confidently afiirmed.'^' 



^ At tlie date of this publication, it is known that this metal occurs, both as a 

 constituent of the mass copper in Lake Superior, and is also developed in reins in 

 tlie stratification. 



