Copper Collecting at Mamainse Point, Ontario, Canada
By David K. Joyce
Mamainse Point has long been known as a source of copper, in particular, native copper. Since the earliest times in North America, prospectors, explorers and miners have visited the shores of Lake Superior in the Mamainse Point area to search for or mine native copper or sulphides of copper. While the deposits are nowhere near the economic significance of the famous Keweenawan copper deposits across the lake in the Upper Peninsula of Michigan, USA, they have sustained a number of economic mining operations over the years, for various lengths of time, including the Copper Creek Mine and the Tribag Mine. The Mamainse Point area is just an hour or so north of Sault Ste Marie, or “The Soo” as it is affectionately known to Canadians.
The earliest miners were aboriginal peoples who had been finding copper in the area for, probably, centuries before Europeans visited the area. Jesuit missionaries, in the 1640’s noted that natives of the area had been using copper for some time for arrows, knives, and ornaments (Kutz, 1998). The Quebec Mining Company was formed in the 1840’s to mine copper in the vicinity of Point aux Mines, on Mamainse Point and Michipicoten Island, further west. The Quebec Mining Company name is noted on old claim maps of the area.
Alexandre Henry, an Englishman, worked a copper deposit on Mamainse Point in 1770 (Kutz, 1998). Unfortunately, the venture was not successful! Thankfully, his efforts drew attention to the copper deposits located in the area.
Throughout the centuries since that time, various groups and individuals have extracted copper from the Mamainse Point area. I was first intrigued with copper specimens from the area that were found by R. Mielke, of Waterloo, Ontario and his father, around thirty years ago and then, more recently, during 2007. Another acquaintance, J. Paul of East Camden, Ontario found some very well crystallized copper in that area of Lake Superior about 25 years ago. Many other collectors have sporadically found well crystallized copper in the Mamainse Point area over the years, including Gil Benoit and Roger Poulin of Sudbury. Roger and Rita Smirle and Peter Lickley had collected there in the past, as well.
One of the latest groups to visit the area consisted of Roger Smirle of Haileybury, Raymond McDougall of Toronto and me, David K. Joyce, Newmarket, during the fall of 2007 and Spring of 2008. Prospecting and collecting has been made easier, in the last five years, by very low water levels in Lake Superior, due to low snow pack and rain levels in the Lake Superior watershed. Most people consider this to be an environmental disaster precipitated by “Global Warming” and “Climate Change”. Mineral collectors have welcomed the (hopefully, temporarily) low water levels -5 feet or so below “normal”, whatever normal is in a geological timeframe. The low water conditions have left calcite veins, some richly endowed with native copper and chalcocite, high and dry on the rocky shores. Shoreline that was under five feet of water a few years ago was easily accessible in May of 2008 and the fall of 2007!
In addition, there are old mines present in the area, near and on the Shore of Lake Superior or further inland. The old Copper Creek Mine was of particular interest to our collecting group.
The Mamainse point area is largely composed of volcanic rocks; volcaniclastics, amygdaloidal basalts and sediments, covered more or less by unconsolidated Pleistoscene sediments. These rocks are criss-crossed with calcite/silicate veins and hydrothermal fracture systems that often are richly endowed with copper mineralization. The copper is usually in the form of “native” copper or, other times, chalcocite, bornite or chalcopyrite. Only the elemental copper has had much collector interest besides some micro or massive sulphide specimens.
Our prospecting technique was to, simply, hike the shoreline in search of veins that outcropped on the shore. Recall that the shore is very different now than it was five years ago because of low lake levels and the resultant newly exposed shoreline. Lots of newly exposed shoreline!! Although hiking conditions could be rugged, at times, and there were WAY more barren veins than veins with copper in them, it was a pleasant search.
The scenery on this eastern shore of Lake Superior is beautiful. The water is clear, the trees gorgeous and the fact that we collected in late fall and early spring meant that there were few or no black flies or mosquitoes to distract us from the beauty of our search area.
The preliminary trip to Mamainse Point in the late fall of 2007 proved to be successful in locating copper on the shore of Lake Superior. Copper is actually plentiful on the shore and it is easy to find hackly masses. Crystallized copper, however, is much more difficult to come by! Roger and I found a vein just north of Batchewana Bay that had large, rounded crystals of copper. Although the crystals were not sharp, they were thickly deposited and impressive. Unfortunately, these large copper crystals were embedded in both calcite and silicate (quartz and zeolites?) and so were a challenge to expose in matrix (Fig. 33 & 35).
During the Spring trip to Mamainse Point, we found that the water level was 15cm or so higher than it had been in the fall. Makes sense!! There had been very heavy snow fall during the winter and high rain levels during the Spring.
In the Spring we found numerous exposures of copper-bearing veins on the shoreline. A number of the veins (Fig. 7) were solid chalcocite, sometimes with chalcopyrite up to several inches across. Others held leaf copper and, a few, dendritic copper.
Every vein seemed to be different with a varied number of habits of crystallization. Veins that did have nice copper were shallowly excavated with simple hand tools and loaded into packsacks to be worked on later. The basalt host rock was very tenacious after a depth of a few cm.
The copper crystals seem different in every specimen from each different vein. Some were sharp cubes, while others were rounded crystals, thick dendrites, thin dendrites, filigree copper (Fig. 24), to leaf copper.
In the vicinity of the vein with very coarse, rounded copper crystals, copper nuggets were found in depressions in the rock. These were easily located with a metal detector. They were rounded and water-worn but from the look the habit that they exhibited, they were definitely from that vein.
In addition to the copper, well-formed, nicely coloured agates and amethyst can be occasionally found on the shore, as well. D. Joyce did find one very nice light-lilac coloured agate during the search for native copper.
As one would expect, zeolites were encountered in the amygdaloidal basalts, as well as veins and breccias. Although of mineralogical and geological interest, unfortunately, no excellent quality zeolites were found.
We visited the Copper Creek Mine which has not operated for a couple of decades. When R. Smirle had last visited the mine, twenty years ago, there had been a watchman and full mine/mill facilities on site. When we visited in the fall of 2007, there was nothing except a capped shaft. All buildings and dumps had been leveled and bulldozed in preparation for reclamation. The current owners are primarily interested in logging the area and have fixed up roads to facilitate that endeavour.
On the main access to the mine area, the loggers had turned up a copper showing that consisted of chalcocite and native copper (not together) in volcanics. The copper was in a small calcite pod (Fig. 10) in a large boulder that had been turned over by the side of the road and, as well, in-situ, in bedrock, at the same location. We were able to remove some of the calcite-copper from the boulder and bedrock, and, after judicious treatment with sulfamic acid, were able to expose very nice dendritic copper. The copper appeared to be in two generations of growth with the first being delicate fronds of filigree copper consisting of stacked octahedral (Fig’s 35, 37, 37). The second generation consisted of rounded cubes of copper scattered on the first generation copper or on a fine quartz druse that sometimes occurred on the first generation.
Collecting at the mine-site dumps did result in the recovery of some chalcocite specimens with small crystals, massive chalcocite, micro malachite and quartz crystals. Zeolites, calcite and hematite were noted but none that were of high quality.
There are very old workings at Copper Creek Mine consisting of old dumps near adits of old shafts. Near one of the old adits, a showing of copper crystals, in situ, had been located by R. Smirle twenty years ago, on the side of Copper Creek, itself. Some specimens had been removed at that time, and the remainder of the copper was excavated during our May, 2008 visit. There was not very much recovered but enough to provide several good crystallized specimens to each of us. In these specimens, the copper is in a dendritic form consisting of stacked, odd crystals that appear to be twinned octahedra (Fig’s. 26-31) that look like hoppered, dodecahedra. They are octahedra in an interpenetrating twin configuration at 90 degrees to each other. Wonderful! These crystal aggregates were in either calcite or a silica matrix. The ones in the calcite were easily exposed utilizing acetic acid. Sulfamic acid seemed to be very corrosive to these crystals since the surfaces of the crystals are partially weathered to cuprite.
We did not hit any “bonanzas” but we did find some worthwhile copper crystal specimens. There will be copper to collect on the shores of Mamainse Point for the foreseeable future, particularly when water levels are low in the future. Erosion due to ice action, freeze-thaw cycles will further expose old veins for future collectors. If any old mines are re-opened or new mines started, these will no doubt result in some very good quality copper and associated minerals being recovered.