Description of the Bare Hills. 357 



rhombic tables of pearly mica (the mica binaire, of Haiiy, See fig. 

 206) and well defined crystals of titan silico calcaire. On breaking 

 open the mass, I discovered a fine piece of the aventurine feldspar. 

 As this piece of granite was evidently out of place, being surround- 

 ed, on every side, by a magnesian formation, I thought it possible that 

 it might have been brought down the ravine from the heights to the 

 south. With this view I commenced a search up the ravine, and 

 upon the sides, and in the small run of water that winds its way 

 down the hill, I found several pieces of the same granite, in some of 

 which small specks of aventurine were apparent. Near the head 

 of the ravine, at T, where the ground was less broken or but slightly 

 excavated by the rains, I found several pieces more, one of which 

 seven or eight inches long, and two inches thick, contained numer- 

 ous well defined crystals of titan silico calcaire. Another of the 

 same kind of granite contained a substance resembling the phosphate 

 of manganese, but which is still undetermined. Encouraged by 

 these specimens, I pursued my course higher into the skirt of the 

 forest trees, where I found, exposed to view by the heavy rains, the 

 northern border or out cropping of the mica slate ridge (or gneissoid 

 formation) before mentioned. Between the strata of these rocks, I 

 observed small beds or veins of the same granite, from which the pie- 

 ces, found near that point, and along the ravine, had been detached and 

 carried by the currents of water. I have been thus particular in de- 

 scribing this locality, which in my estimation possesses unusual interest, 

 in hopes that should any excavations be made hereafter at this point, 

 the attention of some mineralogist may be directed to it. Inde- 

 pendently of the other minerals found in this granite, the aventurine 

 feldspar alone (one of the most beautiful and interesting substances 

 in the mineral kingdom, and found at no other place in America, ex- 

 cept by Dr. Bigsby, on the borders of Lake St. Joseph,) is a suffi- 

 cient inducemeht to undertake a vigorous search, where there is a 

 prospect of obtaining it in such perfection. 



Passing from this ravine to the west, on the margin of the brook, 

 and distant forty or fifty rods, we come to the opening of another 

 ravine that stretches, like the others, to the south. At the head 

 of this in the skirt of the wood, fine specimens of the ligniform 

 steatite have been found, and perhaps may still be discovered upon 

 the surface. On the brow of the hill, on the west side of the ra- 

 vine at P, also at 2 R and S, other excavations have been made in 

 search of chrome, but I believe without success. 



Vol. XXIV.— No. 2. 46 



