140 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [BULL.2li 
a few hundred feet below the summit of the mountain of the same 
name. The main mass of porphyry between Morenci and Metcalf 
shows evidence of very strong mineralization throughout. A great 
number of fissure veins have been encountered in it, although most 
of them are neither persistent nor strong. Close to the surface the 
ores are apt to spread through a considerable mass of rock, and in 
some cases important bodies of chalcocite, due to secondary deposi- 
tion on pyrite from solutions containing copper, have resulted. 
The granite adjoining this porphyry is sometimes also thoroughly 
altered and impregnated with pyrite and chalcopyrite. This may 
be seen in the narrow canyons of Chase Creek for a mile above Long- 
fellow Incline. While a number of more or less well-defined veins 
have been opened here, the results have not been encouraging. 
GOLD DEPOSITS. 
The gravels lying in front of the older rocks at Morenci and Clifton 
are sometimes gold bearing, though ordinarily the metal occurs in 
very fine distribution. The bench gravels above Clifton, along the 
San Francisco River, contain gold, and attempts have been made to 
work them. The results, however, have not been encouraging. This 
gold is probably derived from a system of veins cropping on thj 
Dorsey and Colorado gulch, a few miles north of Clifton on the wesj 
side of the San Francisco River. The system of dikes mentioned 
above as cutting Copper King Mountain continues in places still fail 
ther in a northeasterly direction, but the ore here contains less copper 
and more gold and silver. Attempts to mine these gold-bearing veins 
have not thus far been attended with much success. 
Another gold-bearing district is that of Gold Gulch, 2 or 3 miles 
west of Morenci. The diorite-porphyry which occurs here contains 
many inclusions and fragments of limestone, and this complex 
geological formation is again cut by many faults. Native gold accom- 
panied by limonite and other products of decomposition has been 
found in many small veins in this district, but the tenor of the ore 
seems very capricious, and the deposits have not yet been proved to 
be of much value. 
The copper ores of Morenci and Metcalf, whether occurring as 
contact-metamorphic deposits or as fissure veins, contain a very small 
quantity of gold and silver, in most cases amounting to little more 
than a trace. At the Copper King mine, however, in the system of 
fiesure veins following dikes of porphyry and granite, a notable 
amount of gold is found, and from here on northeasterly, as noted 
above, this tenor in gold increases considerably. 
