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Deposit Synonyms
Burra Burra; Kooringa Cc#4; Ml 3722; Ml 3723; Ml 3724; Ml 3725; Ml 3726; Ml 3727; Ml 3728; Ml 3729; Ml 3730; Ml 3731; Ml 3732; Ml 3733; Ml 3734; Ml 3735; Ml 3736; Ml 3737; Ml 3738; Ml 3739; Ml 3740; Ml 3741; Ml 3742; Ml 3743; Ml 3744; Monster
Mineral District
Deposit Summary
shear & breccia-hosted Cu mineralisation in host siltstone of the Kooringa Member of the Skillogalee Dolomite. Mineralisation associated with feldspar porphyry volcanics dated at ~790 Ma. Production from 1845-1981 ~2.7Mt ore @ ~3.3%Cu.
Deposit Description
BURRA, mine produced 2.7Mtonne of copper ore in 2 mining phases from 1845-1877, and 1969-1981. During the first phase grade averaged 7%Cu with hand sorting, while from the more recent phase, grade averaged 1.7%Cu. The deposit is located at the intersection of 2 major lineaments trending NNW and WNW. Country rock is the Kooringa Member of the Adelaidean Skillogalee Dolomite, dip variable from 25-85E, with greatest variation in and around the ore. Bordering the dolomite to the W is a breccia mass measuring 800m x 300m, with exotic blocks of metasediment up to 10's m (many near in-situ), and set in a fine-grained calcareous matrix of disputed origin. Copper ore developed in 3 lodes, with much ore hosted by breccia, also occurring in veins, and as blebs, and nodules.
Major ore minerals are malachite, azurite, chrysocolla, minor chalcocite, cuprite, trace libethenite and native copper, and primary minerals chalcopyrite, and bornite. The southern and largest lode is within a near-vertical pipe-like body of intense alteration, with much dissolution of carbonate, kaolinisation, potash metasomatism, chloritisation, and silicification. The most intense alteration is centred near several small, sub-parallel syenite porphyry dykes associated with an extensive zone of sub-aerial volcanics. Phoenix Copper from research of historic records suggest zinc is an important pathfinder element. The age of mineralisation is thought to be penecontemporaneous with intrusion of the porphyry, and deposition of the Kooringa Member, ie 797 +/- 5Ma. A significant quantity of gem quality malachite was produced, being noted for its banding that varied in colour from pale green to almost black.
The Burra mine is now heritage listed and the site would be potentially difficult to access again. 1967 total resource estimate inclusive of areas N and S of open cut, and in main dump was ~3.1Mtonne at 1.71%Cu. Past deep diamond drilling below the orebody has not provided an indication of possible extension of mineralisation at depth. Electromagnetics has outlined several IP anomalies in the Burra area which warrant follow up drill testing including deep anomalies possibly related to sulphide-bearing masses. 3D MT modelling of 10km spaced sample points by Uni of Adelaide identifies 7 conductive structures commencing from 200m below surface. The x-section profile is comparable in size to that underlying Olympic Dam. An independent report was commissioned (Collerson, ASX qtly report, Oct 2018) by Ausmex Mining Group. Key results were; comparable hydrothermal fluid compositions (Co-Cu-Ni-Zn-REE-Au) to OD, potential for the MT conductivity anomaly to represent a metal migration region, significant potential for Co and PGEs. The report pointed out common metal associations from several prospects in the region, and suggested a deep mafic igneous source. They further made comparison between Burra and the ~830Ma Jinchuan Ni-Cu-PGE magmatic sulfide deposit.
With the reopening of the mine in the 1980s, including the presence of a crushing & screening plant established on site, the opportunity arose to process rock for the production of road-base and sub-base material for a local project. In the 1990s crushed rock (Skillogalee Dolomite), was supplied for the reconstruction of the Burra to Morgan Rd on a seasonal basis. Operator was Adelaide Wallaroo Fertilisers, with production ~80,000 tonne. The rock is described as fine grained dolomite/dolomitic siltstone suitable for crushed rock production but with an LA value in the low 20’s suitable for the production of sealing aggregates. The stone is non-abrasive to crush.
Discovery Year
? 1845
Commodities
Copper, Dolomite
Ore Minerals
Azurite, Bornite, Chalcocite, Chalcopyrite, Chrysocolla, Copper, Covellite, Cubanite, Cuprite, Gold, Libethenite, Malachite, Pseudomalachite, Sphalerite
Gangue Minerals
Carbonate, Pyrite, Quartz
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