The Honeymoon Well nickel deposits, located approximately 45 km south of Wiluna (26º40'S,120º25'E), are the most northerly of numerous known nickel sulphide deposits within the 2700 Myr old Agnew - Wiluna greenstone belt (Fig. 1; Marston,1984; Hill et al., 1995; Gole et al., 1998). Both disseminated and massive nickel sulphide deposits are present within the deformed and metamorphosed Honeymoon Well ultramafic complex. Despite alteration to lower greenschist facies serpentine-rich and minor talc-carbonate assemblages igneous rock types can be generally recognised through a combination of preserved relict igneous textures, metamorphic mineralogy and geochemistry. Recognition of igneous protoliths and reconstruction of the igneous stratigraphy show that the disseminated and massive sulphide deposits are hosted by distinctly different komatiitic rocks that in turn reflect formation in markedly different volcanic settings.
Bedrock in the Honeymoon Well area is covered by 50 to 120 m of overburden and most geological data have been derived from 830 diamond drill holes and a similar number of percussion holes as well as detailed aeromagnetic data. Much of these data have been obtained since the early 1990’s and thus were unavailable for earlier studies of the Honeymoon Well deposits (Donaldson and Bromley, 1981; Gole and Hill, 1988). Drill hole core and rock chips have been logged for igneous and metamorphic textures, rock and vein mineralogy, and assayed for a range of sulphide- and lithology-related elements. Igneous rock names are used where appropriate in this report despite complete metamorphic reconstitution of the igneous silicate mineralogy and partial to complete reconstitution of igneous oxides and sulphides.
The current sulphide resource is 155 MT at 0.71% Ni (0.4% Ni cut off, <300 m depth) in one massive and matrix sulphide deposit and three disseminated sulphide deposits. This includes a massive sulphide resource of 2.5 MT at 3.36% Ni. Nickel grades in all the disseminated deposits are slightly to significantly higher than at Mt Keith (460 MT at 0.58% Ni; George, 1996) and at Yakabindie (520 MT at 0.47% Ni; North Limited, 2000) which are hosted by similar komatiite sequences.