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Deposit Synonyms
Mineral District
Deposit Summary
series of 29+ en-echelon, sub-parallel lodes on W-flank of domal fold in host kaolinised siltstone of the Tapley Hill Formation. Production from 1844-1877 69,000t ore yielded 13,700t copper metal product. Resource (1993) ~3.7Mt @ 1.2%Cu.
Deposit Description
KAPUNDA, discovered in 1842, with initial mining as open cuts, then underground. The underground workings extended for >1km strike length along a NNW-trending zone from Dutton Mine in the north to Hillside Mine in the south, after which mineralisation was covered by recent alluvials. Regional structural setting was W flank of a broad domal fold, with axis trend 160-170, and mineralisation closely associated with a NW-NNW-trending structure termed the Mine Fault.
Host rock was deeply kaolinised fine-grained metasediment of the upper Tapley Hill Formation, being dolomitic siltstone, minor arkose and shale. Early miners recognised an empirical relationship between best mineralisation and intensity of kaolinisation. High grade ore occurs in quartz veins in kaolinised "shoots." The lodes occur as a system of 3 main sets of veins, with the most productive trending NNE. There were >29 separate productive veins recorded, and numerous productive branch veins mined from >15 separate shafts. Main lode was the exception, trending 160, dip 30-45W. The vein system was arranged en echelon along a bearing of 315, extending for 730m, width 150m, and worked to a depth of ~146m. Host rock between the veins was mineralised, but was of low tenor. Individual ore shoots were from 45-120cm wide, and from 45-60m long. 3 vertical zones were recognised; an upper impoverished zone leached of ore minerals, extending to a depth of 50m; a lower zone of secondary enrichment ~40m thick, extending depths of 90m; a third zone 30m thick of primary sulphides, with the zones shallowing north. Mining ceased in 1877 when an eastern drive from Harris shaft at the 146m level hit water, with the flow of water into the mine exceeding 1.3 million litres per day. From 1844-1877, 69,000 tonne of ore yielded 13,700 tonne of copper. Production peaked in 1857. Initially ore was exported overseas. Smelting works were put into commission in 1852, with an impure regulus produced for shipment. Later a refining unit was added to produce a high-grade copper product. From 1869-78 a leaching process was established to treat low-grade (2.5%Cu) ore. The end product was a copper cement.
Both syngenetic and epigenetic models have been proposed for the mineralisation style. Essentially mineralisation is stratabound, with copper introduced with hydrothermal fluids into a favourable horizon via faults, and deposited along structural traps, with some remobilisation into later veins. Source of the copper may be from the sedimentary package. Later exploration by geophysics and drilling suggested a large, low-grade resource of primary chalcopyrite-pyrite mineralisation might exist at depth. A 1993 estimated resource was 3.7Mt @ 1.2% Cu. Company IP surveys suggested sulphide mineralisation continued south beneath the alluvium. A 1983 resource figure was 3.574Mtonne at 1.26%Cu.
In 2014 Terramin reported significant Ce, La, and HREE from samples of qz veins in the main pit, best value >20% TREE from sample KP07. They completed selected resampling and assaying of cored holes to the east of Main Fault that had been drilled by Utah Development Co. in the 1970s, and that penetrated intervals of copper sulphide mineralisation at depth. Best values include KD008 73m @ 0.58%Cu from 383m, KD011 38m @ 0.85%Cu from 399m including 11m at 1.89%Cu and 0.1g/tAu from 426m.
In 2017 Thor Mining PLc announced plans to invest in investigations to prove the viability of in-situ recovery (ISR) of copper.
Discovery Year
? 1842
Commodities
Copper, Rare Earths
Ore Minerals
Azurite, Bornite, Chalcocite, Chalcopyrite, Copper, Covellite, Cuprite, Malachite
Gangue Minerals
Kaolinite, Pyrite, Pyrrhotite
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