Summary:
The Wolfram Camp deposit is a quartz-rich pipe-like type deposit, with major element zoning around the pipes (Plimer, 1974). Similar to other pipe-like Mo- W-Bi(+/-Sn) deposits in the Tasman Geosyncline of Eastern Australia, it is hosted in the greisen altered margin and roof zone of a granite mass. Quartz greisens commonly form a rim of several metres wide around quartz pipes, with variable and generally lower grade mineralisation.
The Wolfram Camp Mineral Field is dominated by the Ootann Supersuite granite intrusives and related greisen alteration and mineralisation. Greisens are apparently developed at the upper contacts of intrusives usually capping apophyses, where late stage (post intrusive) gases and volatiles naturally accumulated, and are in contact with overlying hosts, in this case the sediments and volcanics of the Hodgkinson Formation.
Alteration and mineralisation are considered to be related to a post intrusion (or very late stage) aqueous mineralising phase or phases, which produces a greisen. The mineralisation consists of erratic pods, pipes and veins, in which the majority of sulphide, wolframite and molybdenite is contained, scattered throughout the greisen zone, over a width of ~50 m. The greisen extends up to the contact but not into the host rocks.
Morton and Ridgway (1944) noted that in most of the pipes mined to that date wolframite predominated whilst in some instances (Mulligan, McIntyre, Nil Desperandum) molybdenite was the main mineral. In all cases, however, wolframite, molybdenite and bismuth were all present. In most cases it had been noted that the rare metals crystallised separately but intergrowths involving all three were fairly common. They also reported the characteristic development of vugs in the pipes, ranging from “inches to a few feet across”. Occasionally these vugs occupied the full section of the pipe for many feet. The largest vug encountered to that date was in the Enterprise (German Bill) mine with reported dimensions of 20m by 10m by 7m. These vugs were more or less filled with quartz crystals and loose clayey and sericitic material containing a considerable number of minerals including the rare metals.
Underground sampling, mining records and drill results indicate an overall metal ratio of 10 W: 3:5 Mo: 1 Bi. The other sulphide minerals present in the mineralised zone are predominantly arsenopyrite, pyrrhotite and pyrite with trace chalcopyrite, sphalerite and galena. In total these sulphides occur less than the Mo content. The wolframite from Wolfram Camp tends towards the more iron rich variety ferberite (FeWO4) as opposed to the more manganese-rich variety, huebnerite (MnWO4). Mineralogical work undertaken by JKTech Pty Limited (2006 and 2007), on behalf of QOL, identified the following additional minerals in samples carrying low grade mineralisation within quartz greisen and granite samples:-albite; apatite; chlorite: euxenite; fluorite; MnFe oxides; monazite; orthoclase; rutile; sericite; thorite; Ti-magnetite; xenotime; and zircon.
Pipes have been historically the more important economically; they characteristically dip towards the contact and a few were reported to reach the contact and follow it. The course, size and shape of pipes changes abruptly. Pipes with maximum dimensions of as much as 14m x 9m (Murphy-Geaney) are mentioned but any with a diameter of >1.5m were considered good working size. Mined pipes have ranged from less than 1m in diameter to 15m by 10m in plan, and have down-plunge lengths often exceeding 100m. The pipes comprise predominantly glassy white quartz with shoots containing coarse patches of wolframite and molybdenite. The overall known extent of the mineralised pipes at Wolfram Camp covers a strike length of approximately 800m and a depth of approximately 170m. The average width of the zone containing the mineralised pipes is approximately 85m.