At Hammerdown a total of nine gold bearing veins have shown sufficient grade and continuity to be included in reserves. An additional six to eight small or weak vein systems have been identified in the Hammerdown zone several of these have developed into small ore shoots. At Rumbullion, seven veins have ore lenses along part of their strike extent.
The gold bearing veins consist essentially of vein quartz with 5-20 percent pyrite occurring as massive stringers and dense disseminations. Base metal sulphides total about one percent, with zinc content equalling combined copper and lead values. Minor bismuth occurs as native metal as well as the sulphosalt hammarite.
Gold is intimately associated with all sulphide phases, occurring as discrete grains within sulphides, at sulphide grain boundaries and, occasionally in quartz fractures near sulphide grains. There is a direct relationship between sulphide content and gold grade in veins. The gold is always fine grained, with 80 percent being of grain size less than 20 microns and the largest grain size is slightly over 100 microns. Considering the high grades, relatively little visual gold occurs in the deposit.
At Hammerdown, the Main vein systems, designated M1 and M2, are respectively located along the north and south contacts of a fairly continuous, felsic dyke porphyry body with the enclosing sheared mafic volcanics. The M2 vein is the stronger of the two. In places offshoot veins within the porphyry close to the M2 vein, are included in M3 reserves.
The Hammerdown hangingwall veins, designated (from south to north) N, 0, P, and Q, mostly occur in relatively "undeformed" mafic volcanics with a minor iron formation component and leucoxene-bearing mafic dykes. Other felsic porphyry sills/dykes are present, but do not influence the siting of the veins like the porphyry associated with Ml and M2. The veins have longer strike lengths compared to the Main veins.
The Footwall veins labelled (from north to south) L, K, and J are hosted by strongly sheared mafic and felsic volcanics invaded by felsic porphyry sills. At least four other vein sets (LI, Kl, K2, Jl) are present. As with the Main Zone, the porphyries play a significant role in localizing the veining, with the strongest veins occurring along the southern contact of the sills. Dips are near vertical and all Footwall veins are truncated by the Captain Nemo Fault.