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The Potter Mine

The Following is an excerpt from Southampton's,"Valuation of the Potter Mine"

Unless otherwise specified, the following information was obtained from the assessment and exploration files, Resident Geologist's Office, Kirkland Lake.

Circa 1930:

A 35 foot deep shaft was sunk on what would become claim 53955 on the sheared and faulted contact between gabbro and "rhyolite". The shaft exposed pyrrhotite and chalcopyrite which assayed 1 - 2% Cu. Trenching north and northeast of file shaft failed to reach bedrock but exposed several heavily mineralized boulders containing pyrrhotite and chalcopyrite (The Northern Miner, February 23, 1967)


A magnetic survey and diamond drilling (3 holes (totalling 594 feet) were completed by Canadian Johns-Manville Co. Ltd. as part of an asbestos exploration program.


R.S. Potter of Matheson, undertook a diamond drilling program. Hole No.2 constituted the discovery hole, intersecting multiple horizons of banded and "replacement" sulphide mineralization consisting of pyrrhotite with subordinate amounts of chalcopyrite, sphalerite and pyrite in the upper part of a "rhyolitic" band. Total diamond drilling amounted to 10 holes totalling 2,423 feet, most of which were concentrated along a 500 foot strike length.

1953 - 1955:

Centre Hill Mines Ltd. was incorporated and acquired patented mining claims 53946 to 53957 from R.S. Potter. Several holes were diamond drilled in the discovery area each year. In 1954, a magnetic survey was completed (NMI 42A/09 Cu 1). By 1954, the sulphide mineralization had been shown to consist of multiple sulphide horizons which had been traced discontinuously along about 200 feet of strike and to a depth of about 400 feet. The main sulphide lens was reported to average 7.8 feet in width and averaged 1.95% Cu and 1% Zn. In March, 1955, Centre Hill Mines Ltd. acquired unpatented mining claims 61260 to 61271 from R.S. Potter.


Magnetic and geological surveys were completed and approximately 40,000 feet of diamond drilling was concentrated along a strike length of about 1,350 feet.


On the basis of drilling results (in excess of 81 holes totalling 40,974 feet (Thomson et al. 1957)) grade and tonnage estimates of 164,487 tons of material averaging 2.09% Cu were made. The sulphide mineralization was described to occur in 6 shoots or lenses in multiple horizons extending about 1,200 feet along strike and at depth to at least the vertical 600 foot level. A vertical 3 compartment shaft was sunk on claim 53954 (the southeast quarter of the south half of lot 7, concession V, Munro Township) to a depth of 408 feet, a crosscut was established at the 350 level and 42 feet of drifting and 97 feet of crosscutting were completed on the main lens. Two holes totalling eight hundred feet were diamond drilled from surface and about one hundred tons of material were hoisted. Financial difficulties resulted in a mine shutdown in November (Field 1960).


A 250 pound sample from the underground dump was sent to the Mines Branch, Canada Department of Mines and Technical Surveys, Ottawa. Chemical analysis of the head sample returned 3.65% Cu, 1.04% Zn, 0.056% Ni, 0.0075 oz/ton Au, 0.60 oz./ton Ag, 12.44% of Si02, and 32.98% Fe (as pyrrhotite) (NMI 42A/09 Cu 1). Results indicated that sulphide minerals would be amenable to concentration by floatation but that because of the intimate association of sphalerite with chalcopyrite within pyrrhotite, it would be difficult to obtain a clean copper concentrate.


Zenmac Metal Mines Ltd. completed an electromagnetic survey for Centre Hill Mines. The survey defined 10 anomalous areas, three of which were diamond drilled. Four holes greater than one thousand feet in length were diamond drilled along the main mineralized zone. During the period 1952-1959, 110 holes totalling 55,163 feet are reported to have been diamond drilled by Centre Hill Mines (NMI 42A/09 Cu 1).


A proposal was made to move the milling plant of Thorncliffe Mines Ltd. (located at the Buffonta deposit, in Garrison Township) to the Centre Hill Mines property (Coad 1976).


The shaft was dewatered and deepened 266 feet to the 634 foot level and 2 levels (the third, and fourth, at depths beneath the collar of 476 and 602 feet, respectively) were established, A total of 1,032 feet of drifting and 264 feet of crosscutting were completed on the fourth level and 6 holes totalling 534 feet were diamond drilled from underground. Total development work through December 31 amounted to 1,074 feet of drifting and 361 feet of crosscutting (Riddell 1966).


By June, the shaft had been deepened to the 630 foot level (Coad 1976). Six hundred fifty-five fret of drifting and two hundred fifty-two feet of crosscutting were completed with total development work through December 31 totalling one thousand seven hundred twenty-nine feet of drifting and six hundred thirteen feet of crosscutting. Ninety-two additional holes totalling twenty-two thousand, three hundred seventy-three feet were diamond drilled (Riddell 1968). A mineralogical study on selected ore samples was conducted (Petruk 1965).


Centre Hill Mines was reorganized to Munro Copper Mines Ltd. (Coad 1976). The exploration headframe was extended from 65 to 100 feet in height and sheeted with aluminum in anticipation of future production (The Northern Miner, May 19, 1966) The shaft was deepened 336 feet to a total depth beneath the collar of 970 feet, the first, fifth and sixth levels (at vertical depths of 200, 725 and 850 feet, respectively) were established, and construction of an on site mill and concentrating facility was nearing completion. One thousand two hundred eight feet of drifting, four hundred thirty-three feet of crosscutting, and eight hundred ninety-eight feet of raising were completed, bringing total development work through December 31 to two thousand nine hundred thirty-seven feet of drifting, one thousand forty-five feet of crosscutting, and eight hundred ninety-eight feet of raising. Thirty-six additional holes totalling two thousand forty-nine feet were diamond drilled during the year.


Three thousand eight hundred fourty-two feet of drifting, ninety-six feet of crosscutting, and three thousand four hundred sixty-six feet of raising were completed. Aggregate development work through December 31 totalled 6,779 feet of drifting, 1,142 feet of crosscutting, and 4,365 feet of raising. In April, milling began (at a rated capacity of 700 tons per day). During the year, 117,512 tons of ore were milled (Riddell 1969). The concentrates were trucked to railhead at Matheson for shipment and distribution by British Metal Corporation (Canada) (ODM 1968). During the latter part of the year, the mine experienced financial difficulties (Coad 1976).


In April, Munro Copper Mines went into receivership and the mine property and assets were offered for sale. Late in the year, an IP survey (SMDR 000830) and surface diamond drilling were completed. In December, The Patrick Harrison Com. Ltd., a major bondholder and shareholder of Munro Copper Company, purchased the property, mine, surface facilities, and mineral rights and the mine was renamed the Potter mine.

Subsequent mining was to consist of high grading copper and leaving zinc in the ground (Coad 1976, Riddell 1970).


Under the supervision of the Harrison Drilling and Exploration Co. Ltd., 2,162 feet of drifting, 300 feet of crosscutting, and 1,119 feet of raising were completed, with aggregate development work through December 31 totalling 10,840 feet of drifting, 1,441 feet of crosscutting, and 6,529 feet of raising. Eleven holes totalling two thousand three hundred sixty-nine feet were diamond drilled from underground. One hundred one thousand eight hundred two tons of material were hoisted, and one hundred one thousand two hundred twenty-five tons of ore were milled (Riddell 1971).


The shaft was deepened 302 feet to a total depth of 1,272 feet and the seventh, eighth and ninth levels were established at vertical depths beneath the collar of 976, 1,102 and 1,228 feet, respectively. Four thousand four hundred fifty-three feet of drifting, ninety-seven feet of crosscutting, and two thousand forty-five feet of raising were completed to bring aggregate development through December 31 to 15,233 feet of drifting, 1,539 feet of crosscutting, and 8,575 feet of raising. One hundred thirty-five holes totalling twenty thousand fifty feet were diamond drilled from underground. Sixty-three thousand seven hundred sixty-seven tons of ore were hoisted, eighty-seven ninety-five tons of ore were milled, and two million eight hundred eleven thousand two hundred ten pounds of copper are reported to have been recovered. Mine reserves at year-end were reported to be 161,000 tons of material averaging 1.6% Cu (Matten 1972).


Underground exploration and development continued on the seventh and eighth levels and milling resumed in June (after a shutdown due to shaft sinking) at an average rate of 650 tons per day (ODMNA 1972).


Underground operations ceased on March 6 and milling (at an average rate of 595 tons per day) ceased on April 7. The mine was allowed to flood and all surface openings were sealed with concrete bulkheads (MNR 1973).


Much of the mill equipment was sold to Noranda Ltd.


The Property was conveyed to Patrick Harrison Global Investments Limited, a parent company within the Harrison Group of Companies. The Property remained on a care and maintained basis.


The Property was sold to Harrison Mining & Engineering, an offshore company, and optioned to 589171 Ontario Limited, a private exploration company.


Millstream participated in 589171 Ontario Limited's option on the Property by funding and completed line cutting, ground geophysics (magnetometer, VLF-EM and HLEM) and 9 diamond drill holes totalling 5,270.5 feet (1,606.4 meters). The result of this work provided useful stratigraphic information.


Millstream funded and completed a deep penetrating I.P. geophysic survey over the east-west central section of the Property, downhole geophysics on 2 drill holes, and 19 diamond drill holes totalling 31,720.4 feet (9,668.4 meters). The results of this work confirmed the down dip and along strike continuation of the Potter mine stratigraphy and the down dip continuation of the massive (Cu, Pb, Zn) sulphide mineralization previously mined on the bottom level of the Potter mine.

Millstream, through 589171 Ontario Limited's option, exercised to purchase the Property April 03, 1998, on the basis of a purchase price of $4,600,000 with the owner keeping a 2.5% net smelter return (NSR) royalty. 589171 Ontario Limited was compensated with 100,000 Millstream shares for giving up all participation and interest in the Property.

Paul R. Coad
M.Sc. Thesis, U of T, 1976.(excerpt)

History of Development

During the copper boom of the late 1920's a shaft 30 feet deep was sunk at the sheared and faulted contact of gabbro and hyaloclastite in the central portion of the map area now marked as a sulphide pit. The shaft intersected sulphides grading 1 to 2% copper; however, the mineralization had limited length.

In 1952 a drill hole put down for assessment purposes intersected interesting copper-zinc values atop of the hyaloclastite horizon in the east central portion of the map area. A company known as Centre Hill Mines Limited was incorporated in February, 1953 (Canad. Mines Handbook, 1954). From 1952 to 1955 several holes were drilled in the discovery area each year. The results of this work were so encouraging that a major diamond drilling campaign was launched to explore the favourable hyaloclastite horizon then thought to be rhyolite. Accordingly in 1956 nearly 40,000 feet of diamond drilling was carried out along a 1350 foot 1ength of the hyaloclastite horizon. In 1957 a three compartment shaft was sunk to 408 feet. A crosscut was driven on the 350 foot level and 30 feet of drilling was done along the top of the hyaloclastite horizon. Financial difficulties at this time resulted in a temporary cessation of work.

In 1959 Zenmac Metal Mines Limited carried out an electromagnetic survey over the property, for Central Hill Mines Ltd.. Drilling of some of the anomalies and the hyaloclastite horizon followed.

In May 1962, a proposal was made to move Thorncliffe Mines' milling plant located in Garrison Township to the mine property. The mine remained virtually idle up until 1964 when underground exploration was resumed. By June, l965, the shaft was deepened to 630 feet and two new levels opened at 350 and 600 foot depths (Canad. Mines Handbook, l965). In February, 1966 the mine was renamed Munro Copper Mines Limited. The mine began to produce copper in 1967. In the same year the shaft was extended to 970 feet, opening 6 levels with the deepest at 850 feet. The mill started production in April of the same year at a rated capacity of 700 tons/day. The mine experienced financial difficulties in the latter part of 1967 and went into receivership shortly after. In June 1968, property and assets were put up for sale.

In early 1969, the Patrick Harrison Company Limited, a major bondholder and shareholder, purchased the property and facilities. The mine was renamed the Potter mine at this time. The deposit was high-graded for copper with the zinc being left in the ground. In August 1972, the mine closed down and remains idle to this day. The mine is presently full of water and has been put up for sale. Much of the mill equipment was sold to Noranda Ltd. in 1975, however no one as yet has expressed an interest in purchasing the mine.

Between 1967 and 1972, 477,572 tons of ore were milled. The average grade of the ore milled was 1.63% copper and 1.5% zinc with 0.1 - 0.5 oz. Ag per ton and traces of gold. 2005 Millstream Mines. All rights reserved