From a 1926 report:
The Green Monster Mining Co.'s property of 68 claims is mainly 3 to 4 miles southeast of Jerome, but two of the claims are 1 mile south of Jerome. The main shaft, 930 feet deep, is said to bottom in diorite. On the 500-foot level the northwest crosscut reached the Revenue vein and at 600 feet encountered the "quartz porphyry " contact, which contained some chalcocite and chalcopyrite in a highly kaolinized leached zone. The Gorge tunnel is on the Cliff claim, north of the Equator property, and was once owned by the George A. Treadwell Mining Co. The tract contains several large jasper outcrops, and that of the Cliff claim shows commercial ore at the surface. The Cliff shaft connects with the Gorge tunnel. Drifts started both east and west on a mineralized contact of "quartz porphyry," and diorite developed a low-grade ore body which, 100 feet below in the tunnel, seemed to be bottoming in " quartz porphyry." Work on the property was discontinued in 1919. The Brookshire tunnel, in the northern part of the property, is 3,000 feet long on the contact of greenstone and diorite belonging to the same complex. Quartz with much chalcopyrite is exposed on the dump.
The Verde Combination Copper Co. has 33 claims south of Mescal Canyon, 1 mile southeast of Jerome, and west of the Gadsden. The developments comprise a shaft 1,300 feet deep sunk in green-stone a short distance west of the Jessie fault. Some work was in progress in 1922. The shaft connects with extensive workings in Mescal tunnel, which shows the great Verde fault, also 2 feet of 5 per cent copper ore in a fissure vein, and two promising contacts with stringers of copper ore. The old workings at the south end of the tract include two shafts, 640 and 500 feet deep, showing diorite with stringers of copper ore, and a 75-foot tunnel that opens a 3-foot quartz vein.
From a 1939 reporting of the Verde Combination Group:
The 1300 foot shaft (sunk in green-stone) connects with extensive workings in the Mescal Tunnel, which shows the great VERDE FAULT, also 2 feet of 5% copper ore in a fissure vein, and two promising contacts with stringers of copper ore. The SPOKE and CHAUTAUQUAAN, two valuable claims, may be included in this group if desired. Good ore on surface of SPOKE claim. Gossan outcrops on CHAUTAUQUAAN claim.
From a 1958 report:
A large block of claims north and northeast of the Copper Chief is owned by this company. The main shaft is east of the Verde fault and north of the road leading to the Copper Chief mine. Precambrian rocks are exposed in the canyon below the Tapeats sandstone, and the collar of the shaft is in quartz porphyry. Fragments of quartz porphyry, Shea basalt, and tuffaceous sedimentary rocks are on the dump. Specular hematite veinlets appear in many fragments, but no sulfide minerals were observed. According to Lindgren, the shaft is 930 feet deep and on the 500 level, a northwest crosscut contacted the quartz porphyry containing chalcocite and chalcopyrite in a highly leached zone. West of the Green Monster shaft and of the Verde fault, an adit level containing about 800 feet of workings, explored a northeastward-trending gossan. It is reported that some gold was found.