(22) 
found here is particularly deserving of attention; it 
consists of a dark brown friable stone, strongly 
‘oloured by iron, or manganese, and in which, are 
cavities, having easts of shells, trochites, and of other 
animals. Of these animals, the original substance 
appears, in some instances, to be totally, and in 
others, partly decomposed and gone;—but all the 
‘cavities are lined with a brown, flat, rhomboidal, 
crystal,* containing a considerable portion of Magnesia. 
*—I obtained these specimens, a few years since, when a portion of the 
rock, called Bunker’s Hill, was removed, for the purpose of enlarging that 
part of the Dock-Yard where it is situated. 
