The Silvertip mineralization is a silver-zinc-lead Carbonate Replacement Deposit (CRD) with metals content, polyphase mineralization, abundant replacement textures, pyrite pseudomorphing pyrrhotite, and wallrock alteration reminiscent of many of the manto-chimney CRD’s of Mexico and the western US

These economically attractive, polymetallic systems can stretch continuously from copper-gold enriched skarns near intrusion contacts in the “proximal” part of the system, to massive sulfide manto and chimney deposits with no exposed igneous relationship in the “distal” areas. Traditionally these deposits have been considered difficult exploration targets due to a paucity of peripheral indicators to mineralization such as hydrothermal alteration or consistent relationships to breccias or structures.

The Silvertip mineralization consists of silver-lead-zinc massive sulphide, formed by hydrothermal replacement processes in McDame Group limestone. In Silvertip terminology, it is known as “Lower Zone”. The main mineralized zones are not exposed, lying between about 50 m and several hundred metres beneath the surface, and covered by the Earn Group. These zones are mainly north of Silvertip Mountain and east of Camp Creek. The ‘Silver Creek’ area is in the west and northwest; the ‘Discovery’ area lies farther east and at greater depth; and the ‘Discovery North’ area, lying to the north, has received relatively little attention to date, but is likely continuous with the other zones.

Another type of lead-zinc sulphide mineralization is present on the property, namely Early Mississippian syngenetic ‘sedex’ deposits associated with siliceous to baritic exhalite subunits in unit 2A of the Earn Group.

Most of the mineralization defined so far occurs at the top of the McDame limestone, at or near the unconformable contact with the Earn Group, although significant sulphides are also present much deeper in the McDame. The massive sulphides are in the form of gently plunging tubes, or cape shaped mantos, up to about 20 m thick and 30 m wide, and in places extending for at least 200 m. Narrower and thicker bodies of massive sulphide, between 20 and 30 m thick, have been intersected locally by past drilling, and are probably discordant, vertically oriented (minor) chimneys connecting mantos at different levels.

Contacts between the massive sulphides and the host limestone can be remarkably sharp, but transitional zones of alteration (silicification, dolomitization) and recrystallization and brecciation are common (not all the dolomitization is related to the mineralization event – some is much older).

The mineralization consists of early-formed pyrite, pyrrhotite and sphalerite and lesser galena, and a slightly younger, higher temperature, sulphosalt-sulphide suite of minerals. The latter contain the main silver-bearing phases including pyrargyrite-proustite, boulangerite-jamesonite and tetrahedrite (freibergite), as well as silver-rich galena. Quartz and calcite are the main gangue minerals and locally fill late-stage vugs and cavities. Brecciation of sulphides, mixed with limestone vein quartz and calcite, attest to multiple phases of fluid infusion and intra-mineral, solution collapse processes.

Extraction of the mineral resources would use drift and fill methods, with cemented rock fill (first 2 years) and paste backfill (year 3 onwards) used to fill open voids. It is expected that up to 50% of the mill tailings could be sent back underground, significantly reducing the size of the tailings area. The mine would be developed via a new ramp and the existing main decline for the transportation of personnel, equipment and materials, as well as transport of the mined resources to the surface for processing. Additional primary development would include two ventilation raises, escape way raises and level access drifts. A total of 5,700 metres of primary and secondary underground development is contemplated during the 21-year mine life.

Mineral processing will use differential flotation to produce lead and zinc concentrates for sale to a third party smelter. Concentrates will be bagged and delivered to the port of Stewart, BC then to smelters overseas. Numerous consultants have conducted metallurgical work on the Silvertip Project. The PA used the average recoveries of all tests completed to date (all pre-1999), that is, recoveries of 75.8 % for silver, 85.5 % for lead and 82.9% for zinc, with silver reporting to the lead concentrates, which will contain 2,000 to 3,000 grams silver per concentrate tonne. The lower silver recovery rate of 75.8% may be due in part to historical attempts to maximize zinc recovery. New metallurgical work is currently being conducted by SGS Mineral Services.