302 The American Geologist. November, 1897 
am able to note only in a general way a marked change in the 
lithologic type at the cross ravine sviggestive of the Huronian 
I succession or contact, ) While the schists on the northeast 
\ side seem to be exclusively acid, the mine schists opposite are 
1 essentially basic, pyroxene and amphibole predominating. 
I Massive amphibolite is the prevailing rock for several miles 
I to the south. Tucker hollow, back of Cranberry ridge, has 
been excavated from this formation. Much of its detritus, 
weathering with exfoliation of ferric oxide into rounded 
forms, externally resembles limonite. This circumstance 
has led without discrimination to n, futile search for this ore 
on the Perkins tract. On the state geological maps the Cran- 
berry mine is made to appear within the Huronian area. 
This is an error. But the concealed Huronian contact is 
probably in Cranberry ridge, and very close to the mines, that 
is, not far back of the railroad bank and in part coincident 
with the cross ravine above mentioned. This probability 
rests upon the assumption that the weathered amorphous and 
sharply folded schists exposed in the railway cuts represent 
that division of the Algonkian series. 
The ore developments at Cranberry, though somewhat 
obscurel}^ defined, are in the form of lenses or lenticular 
masses differentiated by the presence of magnetic iron ore 
within the compass of a remarkably persistent stratiform belt 
of pyroxene passing into amphibole, the former prevailing. 
This passes into epidote and magnetite by alteration. The 
marginal material of the ore lenses is highly epidotic especi- 
ally in the upper workings. Here transition from pyroxene 
into magnetite is notably through a margin of epidote. 
While the interior parts of lenses are characterized by moder- 
ately rich or concentrated magnetite free from epidote, the 
lenses niay be said to graduate outward into p3'roxene- 
epidote of low grade. The more crystalline as well as the 
richer ore possesses the cleavage of pyroxene and is free from 
epidote. Genesis of the magnetite from pyroxene thus aj)- 
pears to be indicated on the one hand with development of 
epidote, and on the other hand, in the case of rich crystal- 
line and more or less distinctly pseudomorphic magnetite by 
replacement without development of epidote. Epidotization 
of pyroxene from weathering action is practically limited to 
