Burrandana
Introduction
The first record of discovery of mineralisation in the field was in 1872 when lease applications were taken out over the tin lodes on Clifton Hill, now known as the Victory Tin Mine. Prospecting on the Burrandana veins began in 1880 where approximately 100 different reefs have been worked at various stages until 1959. Total recorded tin production, mainly from the Victory Tin Mine is 6.235 tons which ceased in 1931. Total recorded production of tungsten concentrates from the field is 15.178 tons. The most recent work in the Burrandana field was conducted by The Shell Company of Australia Limited from 1979. Several programs of exploration mapping, sampling and drilling occurred as the region was considered prospective for a low-grade, large tonnage tin-tungsten deposit.
Figure 1. Locality map of Burrandana
Regional Geology
Burrandana is situated at the southern end of the New South Wales Tin Belt which trends in a north-westerly direction. The New South Wales Tin Belt was formed during the Early to - Mid Palaeozoic by the intrusion of Siluro-Devonian granites within Ordovician sediments. The consequence of this upheaval has produced a thin capping of meta-sedimentary units of the Tamut Pond Group overlying granites. This Tin Belt is characterised by numerous small tin and tungsten prospects that have been worked intermittently over the last 100 years and include the Ardelathan Tin Field, a major tin producer in Australia.
Project Geology
The Burrandana project area is comprised of a thin capping of poorly out-cropping fine-grained siltstones, schists, hornfels with minor quartzite and mudstones that have been intruded by several phases of granites, known locally as the Burrandana granite. The metasediments have undergone regional metamorphism with less common, irregular, contact metamorphism with granites and Aplitic leucogranitic dykes. Three distinct styles of mineralisation are generally recognised throughout the tenure, predominantly concentrated at the contact horizons between medium-grained altered muscovite granite and metasediments. The bulk of mineralisation historically mined throughout the Burrandana Hills consists of wolframite-bearing quartz veins trending N-S that have been extensively mined to a varying degrees. Minor cassiterite and traces of bismuthinite, pyrite, arsenopyrite, chalcopyrite, sphalerite and scheelite are associated with veining. Highly anomalous cassiterite occurs within greisen and occurs as a selvage between granite and quartz veins as well as infilling joints within the granite. Coarse-grained cassiterite occurs within quartz veins within the metasediments where there is a spatial relationship to aplitic dykes or granitic necks intruding into metasediments. This relationship is exemplified by two occurrences at Tin Hill and one at Carter’s Hill where Shell Australia collected a rock chip sample of granitic/aplitic vein material that was assayed at 10,400ppm Sn.
Figure 2. Photo of Carter's Hill, Burrandana.
Previous Exploration
The Shell Company of Australia PTY. LTD. acquired the Burrandana license area with a view to delineating a large, low-grade, tin-tungsten resource. Styles of mineralisation considered to be possible targets in the area included greisen cap, stock-work vein systems and sheeted vein systems. Detailed mapping and identification of mineral occurrences and areas of alteration by Shell Australia commenced in 1979, which paved the way for a rock chip sample program where 1355 samples were taken on 50m x 50m spacing’s. Approximately 33% of samples were of muscovite granite, the remainder biotite-muscovite granite. Assay results across the northern region of the exploration license showed that prospective mineralised granites in the area contained background levels of both tin and tungsten and were thus of a low exploration priority. Biotite-rich granites located in the south-east of the tenement also returned low level responses. The most prominent tin and tungsten anomalies within the EL were samples taken from muscovite granite across the Tin Hill – Carter's Hill crests. High assay results were found to correspond with a North-South trending quartz vein system, stretching across the top of the hill. Biotite granites along the flank of the hills reflected background levels. Drilling of the tenement commenced at the beginning of 1980 with multiple percussion drilling programs across the Eastern and Western ridges totalling 996m from 14 holes drill-holes. Four diamond drill-holes targeting strong geochemical anomalies were completed at the Carter’s Hill prospect for a total of 401.3m. Several other targets in the region were drilled during this period to follow up on tin and tungsten anomalies and are displayed in Figure 2. Drilling encountered over 90m of altered muscovite granite beneath a siliceous quartzite capping, containing sulphides, cassiterite and quartz veining with the majority of mineralisation found between 20-80m beneath the geological contact. Significant intercepts are displayed in combined Sn-W values in Table 1.
Hole ID
Significant Intercepts
PBT1 6m @ 540ppm combined Sn + W. PBT2 52m @ 387ppm combined Sn & W, including 16m @ 770ppm combined Sn + W. PBT3 8m @ 0.12% Sn, 0.1% W from 52m. Includes 2m @ 0.19% Sn, 0.1% W from 54m. PBT4 4m @ 637ppm Sn, 0.96% W from 34m. Includes 2m @ 0.11% Sn, 1.29%W from 36m.
PBT5 6m @ 340ppm Sn, 0.5% W from 18m. Includes 2m @ 475ppm Sn, 1.25%W from 18m and; 2m @ 425ppm Sn, 0.18% W from 22m
PBO 14 12m @ 0.24% combined Sn + W including 1.5m @ 1.54% Sn + W. PBO 16 9m @ 0.07% combined Sn + W
Hole ID
Significant Intercepts
4m @ 637ppm Sn, 0.96% W from 34m. Includes 2m @ 0.11% Sn, 1.29%W from 36m.
6m @ 340ppm Sn, 0.5% W from 18m. Includes 2m @ 475ppm Sn, 1.25%W from 18m and; 2m @ 425ppm Sn, 0.18% W from 22m
9m @ 0.07% combined Sn + W
Table 1. Summary of significant intercepts at Burrandana by The Shell Company of Australia, 1979-1982
The best intersections are associated with intense greisenisation and quartz veining at the top of the granite roof. The intersections within holes PBO14, PBT2, PBT3 and PBT5 suggest a relatively flat style of mineralisation is located at the roof of the granite, close to the contact with the overlying metasediments. It was concluded that the geological environment was favourable for a griesen or vein deposit within the area between the Tin Hill crest and drill-hole PBO14 and that further drilling is required to ascertain the style, extent and orientation of mineralisation.
Figure 3. Summary drilling plan at Burrandana. Displays collar locations for drilling conducted by The Shell Company of Australia, 1979-1982
Wolf Minerals at Burrandana
Field work undertaken by Wolf in 2008 included the ground truthing of the Tin Hill, Carter’s Hill, Scout Hall East and Blackboy prospects for historic workings, previous drill hole collar positions and geological mapping. No obvious drill hole collar positions were positively identified. Five rock chip samples were taken from costeans on Tin Hill, located adjacent to drill holes PBO14 and PBT 3-7. All assays were sent to ALS in Orange for assaying of W and Sn.
Significant assay results of 1.76% W and 0.09% Sn were recorded from sample Sam3 within a costean.
Geological observations confirmed what had been reported within a review of previous literature, namely historic workings of shafts, pits and costeans centred on narrow wolframite bearing quartz veins hosted within muscovite granite and metasediments at the contact horizon. Mineralisation at the Tin Hill prospect remains open to the west and the south along the muscovite granite - metasediment contacts.
The next phase of exploration will invlove an infill RC program aimed at delineating the extent of mineralisation and to further the understanding of the current geological model.