* Claim status information from Millstream Mines Ltd.
MINE GEOLOGICAL SETTING:
The Millstream Mines Limited property hosts the Potter Mine Cu - Zn VMS deposit located in the south half of Lot 7, Con V, Munro Township on patented mining claim L 53954. A resource estimate1 that includes past production and proven and possible reserves to the eighth level (-1100' from surface) is 544,000 tonnes grading 2.05 % Cu, 1.67 % Zn with minor credits of silver (0.1 to 0.5 oz/t.) and gold (0.001 oz / t).
The Potter Mine deposit occurs within a layered volcanic regime dominated by ultramafic komatiitic and minor mafic tholeiitic volcanic sequences of the Kidd -Munro assemblage. The volcanic stratigraphy in the mine area strikes east -southeast, dips steeply north, and faces stratigraphically north. The volcanic sequence occupies part of the south limb of an east - southeast striking regional synclinal structure that plunges to the northwest.
Within the mine area are komatiitic ultramafic volcanics represented by a series of layered, differentiated flows, with minor interflow breccia and agglomerate intervals. The layered sequence consists of differentiates ranging from dunite to peridotite to pyroxenite to basalt in composition. Texturally the flows can be massive and uniform, polysutured to spinifex textured. Textures such as cumulate layers of equant serpentinized olivine crystals, glomeroporphyritic plagioclase, and oikocrysts of pyroxene with poikolitic olivine occur.
Conformably within the layered komatiitic volcanic succession in the mine area1 there are Mg tholeiitic basalt fragmental horizons, known as hyaloclastite. This mafic fragmental unit consists of well sorted pea-sized angular to subrounded basalt fragments that can be clast supported, and contain quenched textured basaltic glass within a matrix of ash, interstitial calcite: and up to 20 % disseminated carbonaceous material. The hyaloclastite horizons have acted as a permeable and porous host assemblage for sulphide deposition and are the immediate host rock for the Potter mine Cu - Zn mineralization. There are at least three hyaloclastite horizons in the west mine area that coalesce eastward, of which the upper horizon is the most heavily mineralized.
The sulphide mineralization at the Potter Mine consists of fine grained
pyrrhotite, chalcopyrite, sphalerite, pyrite, and minor native silver occurring
as heavily disseminated sulphides, and as thin lenticular massive sulphide
lenses, that are localized within the upper carbonaceous and carbonitized
(calcite) Mg tholeiitic basalt hyaloclastite horizon.2
1 Fyon, JA. et al. 1992 Metallogeny of Metallic Mineral Deposits In the Superior Province of
Ontario; in Geology of Ontario, Ontario Geological Survey, Special Volume 4, Part 2, p 1091 - 1174.
2 Coad, P. R. 1976, The Potter
mine, Unpub. Msc thesis, University of Toronto,
Toronto, Canada, 239P.
The economic sulphides are generally restricted to this upper hyaloclastite horizon, however some sulphides have been remobilized along local shears in the overlying komatiitic flow sequence. The massive ore lenses are zoned from zinc-rich top to copper-rich base. Within the sulphide lenses Fe-rich sphalerite predominates, although some Fe-poor sphalerite does occur near the top of the hyaloclastite horizon. Generally matrix sulphides predominate, and occur near the upper part to the top of the hyaloclastite horizon. Banded pyrrhotite, chalcopyrite, and sphalerite, occur as massive sulphides at the top of the fragmental horizon, at the hyaloclastite / komatiitic flow sequence interface.
The Potter Mine Cu - Zn deposit is believed to have formed syngenetically on the sea floor. (Coad, 1976). The banded nature of the massive sulphides, sharp upper contact with the overlying volcanics and gradational underlying matrix sulphides, copper to zinc metal zonation from base to top, and the inferred presence of a strong chloritic alteration pipe - like zone coincident with zones of high Cu/Zn ratios, are all consistent with a subaqueous exhalite origin.
The age of the Potter mineralization is dated at 2715 Ma which is also closely contemporal with the age of the Kidd Creek VMS deposit dated at 2717 Ma, which also occurs within the same Kidd - Munro volcanic assemblage, north of Timmins, Ontario.
Coad (1976) describes the individual ore shoots to be narrow bodies, 15 - 30 m along strike and averaging 1 m in thickness, with a considerable down dip dimension. The Potter Mine sulphide mineralization has been mined from the 1st level (-200 ft.) with stopes developed through to the 8th level (-1100 ft.). Total production from 1967 - 1972 is 477, 572 tons milled yielding an average grade of 1.63 % copper. The grade of zinc was about 1.5 %, but it was not recovered. The configuration of the stopes on the accompanying longitudinal section yields a strike length of mineralization of approximately 1300 feet from the shaft westward, and to a depth of 1100 feet. Mineralization appears to be open at depth, below the lowest mine workings. In addition, the stope distribution illustrates a steep westerly plunge to the mineralized / mined areas.
1996 - 1997 EXPLORATION PROGRAM:
In 1996, Millstream Mines Ltd. established a grid on the property for geophysical survey control and for drill collar location control. Selected grid lines were surveyed with a MAX - MIN II HLEM system in an attempt to identify potential exploration drill targets.
In July - August 1996 a nine hole diamond drill program totaling 5271 feet and in Feb. - Mar 1997 a seven hole drill program totaling 3930 feet was carried out. The purpose of these drill programs was to test geophysical responses that lay outside to the north, east, and south, of the mine main sulphide / hyaloclastite horizon. In April, 1997 Dave Gamble Geoservices Inc. was contracted to log the drill holes and to produce drill sections for Millstream Mines Ltd.
The holes S - 97 - 3, 4, 5 located south of the mine sulphide horizon and drilled south easterly in the mine footwall rocks delineated several additional hyaloclastite horizons. Hole S - 97 - 6 drilled immediately east of the shaft encountered what appears to be the mine hyaloclastite horizon that carried geochemically anomalous copper and zinc values. Hole S - 96 - 09 collared some 1000 metres north of the mine sulphide horizon encountered graphitic sediments and hyaloclastite intervals similar to the mine setting but stratigraphically facing south. This hole S - 96 - 09 appears to have intersected the north limb of the synclinal structure and may represent the equivalent stratigraphic level of the sulphide bearing hyaloclastite mine horizon on the south limb.
No economic sulphides were encountered in the summer 1996, or in the winter 1997, drill programs. Geochemically anomalous Cu and Zn were reported with the best results up to 1.47 % Cu and 0.46% Zn over isolated short intervals (See drill logs and sections).
The results of the drill program provides useful stratigraphic control in the volcanic assemblages in the mine area for future correlation.
The Potter Cu - Zn ore zone horizon remains open to depth below the existing mine workings. The longitudinal section clearly illustrates the down dip and down plunge potential for further tonnage development below the lowest mined 8th level. The potential is high for delineating further Cu - Zn sulphide ore along the steeply north dipping hyaloclastite horizon, and in the steep westerly down plunge direction from the existing stoped areas. Exploratory deep drilling has not been carried out systematically beneath the down dip or in the down plunge direction to any significant depths below the existing mine workings of the Potter Mine ore deposit, however D. J. Sykes, P Eng., in a 1972 report, indicates that "four drill holes beneath the eighth level indicate that the ore continues for another 300 feet at least". Also, the favourable land position extending 2.0 km along strike to the west and 1.0 km to the east of the mine provides excellent scope for further exploration.
In addition, since mining activities ceased in 1972, there has been a + 25 year gap of acquiring and interpreting modern geophysical data, such as the current geophysical technique of down hole Pulse EM testing to explore the mine sulphide horizon at depth.
It is recommended that a deep drill testing program be undertaken to explore the highly prospective area of ground 300 - 400 feet below the 8th level mine working area, in an attempt to intersect the down dip extension of the economic hyaloclastite / sulphide horizon.
Down hole Pulse EM geophysical surveys would aid in determining follow-up drill testing targets, or for wedging off these initial proposed holes if lateral or deeper anomalous EM responses are indicated.
It is recommended that 5 NQ sized drill holes of 600 metres each, totaling
3000 metres, be conducted for this initial deep drill testing program.
These holes would test the projected ore zone strike length of the area
lying between old mine grid sections 8000 ft E to 9000 ft. E or on the
1996 grid 17 + 50 m W to 14 + 50 m W and at a level 375 ft below the existing
underground mined area and at a total depth of 450 metres (1476 feet) below
surface. (See accompanying Surface Plan, Longitudinal Section, and typical
Drill Section Layout 1:2500) The following holes are recommended to be
drilled at 180 deg. azimuth and at a collar inclination of - 60 deg. All
effort should be made to monitor and to minimize drill hole deviation to
reach the proposed target areas. The proposed hole locations are:
The recommended drill program to test the highly prospective ground below the existing mine workings has an excellent potential to intersect the down dip extension of the economically significant hyaloclastite sulphide bearing horizon Encouraging results from this proposed drill program, coupled with the existing u/g infrastructure, would make this property an attractive exploration project for future evaluation and possible development, if warranted. The proposed drill program is the next logical step, and offers excellent exploration potential for further sulphide discoveries.
Dave Gamble DGGI
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