USGS Professional Paper 144 p 175

     LAKE SHORE TRAP HORIZON

     The sandstone immediately under the Lake Shore trap is mineralized at several points on the north side of the Porcupine Mountains and was developed years ago in the Carp Lake mine. From 1860 to 1865 there was a recorded production of 33,935 pounds of copper. The copper of this mine has replaced red sandstone immediately below the Lake Shore trap. The sandstone is mineralized from a few inches to a few feet from the trap. Where mineralized, the red sandstone is bleached to gray. No hydrocarbon was noted in this sandstone. On the dump of the Carp Lake tunnel is vein material consisting mainly of calcite and in part an iron-bearing carbonate with included chalcocite.

     The sandstone has been shown to be mineralized over a distance of several thousand feet near the Carp Lake mine and is reported to be mineralized at several other points along the north slope of the Porcupine Mountains.