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Gold/Mining/Energy : Donner Minerals (DML.V) -- Ignore unavailable to you. Want to Upgrade?

To: donkeyman who wrote (925)	11/10/1997 2:17:00 PM
From: Kent C.	Read Replies (1) \| Respond to of 11676

Thats a good question, maybe Terry can answer it, here's what I found: The Voisey's Bay Deposit The sulphide mineralization at Voisey's Bay comprises predominantly pyrrhotite, pentlandite and chalcopyrite; magnetite is also widely developed within the sulphide mineralization. The ore minerals are locally exceptionally coarse grained. As noted above, the Voisey's Bay mineralization is disposed in several different settings. Without exception, however, the host rock to the sulphides is massive troctolite, one of two major units that comprise the Reid Brook intrusion, as I outlined in my previous communication. The following is an overview of the geological features of the three major concentrations of sulphides known at this time, and the interpretation of the relationships between them. For details please refer to Naldrett et al., (1996) and to Ryan (in press). The original discovery is within an east-west trending troctolitic dike (Figure 1), which has a variable dip to the north and a maximum thickness on the order of 100 metres. Mineralization in the dike occurs both as disseminated sulphide within a troctolitic groundmass, and as pockets of semi-massive to massive sulphide that locally enclose contemporaneous silicate minerals (plagioclase, olivine, pyroxene). The Ovoid, to the east of the initial discovery dike (Figure 1), is an exceptional ore body, a bowl-shaped accumulation of sulphides, in places over 100 metres thick, separated from underlying gneiss by a rind of troctolite containing numerous fragments of gneiss. This sulphide mass is roughly elliptical in plan view and is approximately 450x250 metres in size. The reserves in the Ovoid are estimated to be at 31.7 million tonnes, having an overall grade of 2.83% Ni, 1.68% Cu, and 0.12% Co. The Ovoid is interpreted by Naldrett et al., (1996) to be the down-faulted base of the overlying magma chamber - the part that is missing from the dike setting. Drilling of massive troctolite to the east of the Ovoid has encountered a significant linear zone of sulphide near the contact between the troctolite and the underlying gneiss, at a depth of over 600 metres. This discovery is referred to as the Eastern Deeps (Figure 1), and is interpreted by Naldrett et al., (1996) to correspond with the line of intersection between the sulphide-bearing feeder dike and the base of the Reid Brook magma chamber. This discovery verified the geological reasoning of Ryan et al., 91995) that the massive troctolitic rocks east of the discovery dike represented a preserved higher stratigraphic level in the Reid Brook intrusion, and that sulphides might be resident at the base of the intrusion in that area. The indicated resources for the Eastern Deeps deposit are on the order of 50 million tonnes containing 1.36% Ni, 0.67% Cu, and 0.09% Co. The Eastern Deeps deposit has not been fully delineated at present, but the geometry of the base of the magma chamber in this area indicates that there may well be an extensive zone of sulphides present along strike of the known ore. Similarly, the dike-hosted part of the deposit, west of the initial discovery outcrops, has the potential for hosting more ore, especially in appropriate traps within this part of the sub-chamber plumbing system. taken from gallery-gold.com cheers, Kent