ORES OF COPPER 05 
Hecla Shoot, is in conglomerate ; it is about 3 miles long, 
and varies from 12 to 15 feet thick, and has been mined 
to the depth of over 6000 feet. The ore is low grade, and 
has paid to work toa value of ‘55 per cent. of copper, for the 
vein stuffs are brittle and cheaply crushed by stamps, and 
the metallic copper is separated by simple washing. The 
copper was at one time considered to have been a primary 
constituent of the ferro-magnesian minerals in the diabase; 
but the igneous rocks only contain copper where it has been 
Secondarily introduced. The rocks near the ore have been 
traversed by hot alkaline plutonic water which probably 
obtained the copper by the solution of detrital grains in 
the sandstones. The channels form the shoots, some of 
which enter the lavas; the reduction of the solution by oxi- 
dation of ferrous iron in the diabase or of some ferrous mineral 
In the conglomerate led to the deposition of the native 
Copper.