History:
The first major discovery of copper in Australia was at Kapunda in South Australia in 1842 when Francis Dutton found copper ore whilst searching for lost sheep. Mining began with the removal of surface ore and had progressed to underground mining. Typically, the miners were Cornish, labourers were Irish and smelter specialists were Welsh. In 1865, the mine was leased to a Scottish company which switched to open-cut mining methods. Mining continued until 1879, with a total recorded production of 69,000t of ore. Kapunda can claim the first open cut mine in Australia.
Geology:
Local geology consists of folded and faulted sediments of the Tapley Hill Formation. Most of the mineralisation itself occurs within what has been termed the "Kapunda Mine series" by Rowlands et al, 1978. This unit is 500-700 m thick, consisting mainly of massive siltstones that contain pyrite and pyrrhotite. Mining at Kapunda was mainly of secondary ore, created by supergene enrichment of the vein mineralisation, Dickinson, 1953. Supergene enrichment occurs at the base of the oxidized portion of an ore deposit. This a natural chemical process that produces secondary sulfides with metal contents higher than those found in the primary ore body.
Geoscience:
Mining techniques can be divided into two common excavation types: sub-surface (tunnel) mining and surface mining (open cut).
>Open cut mining involves digging and/or drilling and blasting to remove the ore for processing. Often there is overburden or waste rock material, which must be removed before the actual ore can be acessed.
>Sub-surface mining consists of digging tunnels and shafts into the earth to the reach buried ore deposits. Ore, for processing, and waste rock, for disposal, are brought to the surface through the tunnels and shafts.
Earthcache:
At the listed coordinates you are standing in the Stockyard Open Cut. This location is of interest as you can also see a good example of tunnel mining. Examine the rocks around you and answer the following questions. You may log a find immediately but you should send your answers to the cache owner by email or message.
-Describe the shape of the open cut? What has caused this shape?
-There are many colours visible in the open cut. Green deposits are low grade copper ore. Can you see any brown/black high grade ore? Why?
-Cornish miners were world renown for their tunnelling skills. Could you stand up in their tunnel?
