26 VOLCANIC ROCKS OF SOUTH MOUNTAIN. [bull. 136 
to and beyond the Stale line into Maryland. This belt lies along tin 
contact between the acid and basic eruptives. 1 
The principal localities where shafts have been sunk within this bel 
are. the Snively copper mines, the Rnssel farm (the Bechtel shaft), tin 
Reed copper pits, the Bigham copper mine, and the Headlight mine 
(See map, PI. IIT.) To the east of this belt, on the road between Fair 
field and Fountaindale, a fifth old copper shaft is located. 
The Snively copper mine, which is a mile north of the Monterey dis 
trict, was not visited by the writer. 
Frazer reports that the copper is associated with quartz, epidotn 
rock, and azurite. 2 
At the Rnssel copper mine, which is located on the Rnssel farm, at tin 
fork of Copper linn, native copper occurs in quartz veins, associatec 
with calcite, in a very siliceous epidotic rock, an epidosite. The mate 
rial thrown out at the lower shaft was amygdaloidal greenstone; at tin 
upper or Bechtel shaft, an acid slate, which indicates that the coppe 
belt is along the contact between the two igneous rocks. 
The Reed copper pits lie on the north side of Toms Creek, at tin 
forking of the highroad near Spring Run. It has not been worked fo 
forty years, and there is nothing visible to indicate the character of th< 
copx^er occurrence. The dump pile shows scoriaceous greenstone: 
with malachite stains. Dr. Snively reports that native copper occur 
here in quartz veins. 
The excavation for copper ore on the Bigham property, which lie 
just northwest of the forking of Gladhills road, furnishes interesting 
material for the petrographer. It is here that acid amygdaloids havi 
been exposed in great perfection. They are abundantly stained witl 
malachite, azurite, or cuprite. Metallic copper occui\s in quartz vein 
traversing the amygdaloids, and in submacroscopic quantities in tin 
amygdules. In the latter case the copper is frequently surrounded ty 
zones of the oxide and the carbonate. An analysis of these rocks give 
4 per cent of copper. The Headlight mine is tunneled beneath the turn 
pike half a mile (eastward) below the Clermont House. Here the dumj 
pile shows only greenstones, more or less stained with copper carbonates 
This is also the case at the old copper shaft on the Fairfield road 
Asbestos in quartz is quite generally found at these copper mines. 
Throughout this belt the copper is evidently of secondary origin 
occurring in seams and amygdules, where it has been deposited iron 
solution. This occurrence of metallic copper in the igneous rocks o 
South Mountain is interesting because of its similarity to the Lak« 
Superior copper-ore deposits. Its associations are quite analogous 
In the Lake Superior region it occurs in veins, quartzose and epidotic 
in the open-textured amygdaloids (basic), and in interbedded con 
'Frazer says: "The ore belt lies in the orthofelsite which forms this portion of the chain." 
2 P, Frazer, Copper ores of Pennsylvania: Polytechnic lloview, Vol. Ill, 1877, Xo. 16, p. 170; also 
Appendix, Vol. CCC, Seconu Geol. Surv. Pa., p. 310. 
