200 
[Assembly 
When pyrites in large quantities are associated with coal, spon- 
taneous combustion, by the addition of moisture, often ensues, giv- 
ing rise in many instances to so great a degree of heat, as to cal- 
cine and partially fuse the rocks in connection with it. Such com- 
binations are known by the name of false or pseudo volcanoes. 
When the quantity of pyrites is not so great, mere distillation of 
bituminous matter is the result, accompanied by carburetted hydro- 
gen gas. 
Pyrites in decomposing in the presence of carbonate of lime, 
gives rise to gypsum, which seems to have had no other origin, at 
the same time, has produced a yellow pigment, and the largest 
class of our iron ores. In simultaneously decomposing with slate 
or shista containing potash, it forms alum, of which a recent disco- 
very has been made in the vicinity of Fredonia. 
Manganese. Excepting as the chief coloring matter of the sand- 
stone and shale, in which it exists in the state of protoxide, man- 
ganese presents itself as an hydrate, called the brown oxide, its 
powder being of that color. It often invests the fragments occur- 
ring in the brooks, and also the calcareous tufa or honeycomb lime- 
stone. In some localities it forms thin layers in the tufa of h of 
an inch in thickness, with a crystalline or shining appearance. 
This ore of manganese is not used in the arts, affording no profita- 
ble proportion of oxygen. 
At one locality where manganese was found with the tufa, it 
had for some time attracted the attention of the owner of a lime 
kiln, who was convinced that it was an ore of silver, and so far 
from being discouraged, after making many abortive attempts to 
obtain a metallic substance, was convinced that it ultimately would 
prove a fortune for his children. 
Copper, Stains of green carbonate of copper are found at Black 
Rock and at Lockport, arising from the decomposition of copper 
pyrites, which latter species was noticed in other localities, and in 
like small quantity. Very minute tetrahedral crystals of gray 
copper are likewise found in the same limestone at Black Rock. 
Zinc, The only ore of this metal that we noticed, was the sul- 
phuret or blende, being found as mere cabinet specimens in the 
cavities of the geodiferous lime-rock of Professor Eaton at the Falls 
of Niagara and at Lockport. No doubt the carbonate and siliceous 
