ransomk.] COPPER DEPOSITS OF BISBEE, ARIZ. 155 
Bisbee are in the Carboniferous limestones. It is probable that the 
greater number of the ore bodies occur in the granular limestones of 
the Lower Carboniferous, but the distinction between Upper and Lower 
Carboniferous beds can rarely be satisfactorily made underground. 
Some important ore bodies certainly occur in the lower part of the 
Upper Carboniferous. On the other hand, no ore bodies of conse- 
quence have yet been found in the deeper-lying Devonian and Cam- 
brian limestones. In the Copper Queen mine local usage has distin- 
guished an "upper lime " and a "lower lime." As far as could be 
seen, however, this distinction is largely imaginary and is based on 
no constant lithological or structural features. The "lower lime" 
appears to be any limestone lying underneath the known ore bodies. 
It is in the main Lower Carboniferous, and the ore-bearing possibility 
of the underlying and Devonian and Cambrian beds is yet to be ascer- 
tained by deeper prospecting. 
Although the ore masses in general are what are generally termed 
"flat" ore bodies, dipping gently with the inclosing beds, they are 
related to other structures as well as bedding planes. , Ore is usually 
found in large masses along the contact of the limestones with the 
main porphyry mass. This contact, however, has not been thoroughly 
explored, and much of the ore along it consists largely of low-grade, 
partly oxidized pyrite. Dikes and sills of porphyry occur in the lime- 
stones at various distances from the main intrusive mass, and the se 
are almost invariably associated with ore in the adjacent limestone. 
In some cases large ore bodies, followed for a long distance in the gen- 
eral plane of the bedding, have been known to turn down almost ver- 
tically alongside a porphyry dike. Fissures in the limestones have 
also undoubtedly influenced the distribution of the ore. 
While the main porphyry mass of Sacramento Hill is often heavily 
impregnated with pyrite, it has not been shown to contain workable 
ore bodies. It is possible that one or more of the oxidized ore bodies 
in the Copper Queen mine were formed by the mineralization of the 
granite-porphyry, but this is a point which the present investigation 
has not yet determined. It is certain that many of the porphyry dikes 
encountered in the workings of the Copper Queen mines show no 
appreciable mineralization, even when in contact with ore. 
Miner alogical character of the ores. — The ores worked by the Cop- 
per Queen Company up to 1893 were oxidized ores, consisting chiefly 
of malachite, azurite, cuprite, and native copper. In the upper 
levels the malachite and azurite occurred in beautiful incrustations 
and stalactites, lining caves in the limestones. These "cave ores" 
have been exhausted, and although oxidized ore is still abundant it 
occurs generally as soft earthy masses, often containing cuprite and 
native copper, and usually associated with large amounts of limonite 
and kaolin. Native copper and crystalline cuprite are still abundant 
in the recently opened workings ot the Calumet and Arizona mine. 
