In Search of Gold - minerals and impact. EarthCache
In Search of Gold - minerals and impact.
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Mount Lyell Mine, located near Queenstown, Tasmania is now a copper mine, producing approx 30,000 tonnes per annum of contained copper (Cu) in concentrate from underground sub-level caving mining operations at 1,000 metres below the original surface.
RECENT HISTORY
This mine was originally discovered by three hardened prospectors - brothers, Bill and Mick McDonough and a Scandinavian seaman, Steve Karlson.
What they found was GOLD!
However it's real wealth was understood later to be in COPPER. Three investors - William Dixon, James Crotty and Frederick Henry took over the claim.
NOTE: the three original prospectors ended their lives in poverty, injury and alcoholism
The three new investors held onto their shares, and lived luxurious lives!
In 1892 the Mount Lyell Mining company purchased this as a copper mine, and open quarry mining continued until 1922.
The Mount Lyell Mining company has produced more than 1.8 million tonnes (Mt) of copper (Cu) and 62 tonnes of gold (Au) and 1,300 tonnes of silver (Ag) until recent times (2012)
Statistics from Copper Mines of Tasmania.
Image from the National Trust of Australia, postcard collection.
GEOLOGY
550 million years ago, associated with the continental plate movement a series of volcanic centres developed forming a line along the ocean floor. As the volcanic cones built up seawater began to circulate, passing through the rocks, dissolving copper, iron and sulphur. The seawater then rose through faults to near the sea floor, where the dissolved material precipitated out in the volcanic sediments as metal rich sulphide minerals.
About 100 million years later, major movement and upheaval - faulting and folding - of the rocks occurred and remobilising the mineralisation, bringing the volcanic rocks up against the Owen congolmerate. Since that time erosion has acted to form the natural surface prior to mining.
Mount Lyell and Mount Owen (nearby) are the remains of the sediment.
Here at "Iron Blow" you can walk out above the open cast quarry of years gone by, and see both the strata of the quarry interior and the environmental impact on it's surrounds.
There is good signage here, telling of the conditions of mining and some history.
COME PREPARED for windy and cold conditions.
ENVIRONMENTAL IMPACT
The local mountains were stripped of trees to feed the furnaces of the smelter of the copper mine. A combination of toxic sulphur fumes and acid rain killed off other vegetation & prevented regrowth. With no forest, the land dried out. Heavy rainfall washed away the remaining topsoil. Sulphur saturated the earth and changed the colours of the soil & rocks to the odd, pastel shades.
The smelters closed in 1969. Mining of gold and copper continues in the area but of course it is with modern mining practices & environmental regulations guiding what they can and can’t do to the fragile environment.
TO LOG THIS EARTHCACHE:
You mUST visit this location, and email me via GC profile or direct - earthcache@wallace.net.nz
DO NOT USE THE GC MESSAGE CENTRE PLEASE !
1. What is the month and year at the end of the brass plaque near the start of the airwalk platform.
2. What is the quote of 1897 about "Causing a stir".....
3. Describe the colour / colours of the walls of the open cast hole
NOTE: If you have visited previously, a new visit is required to log this cache.
OPTIONAL: Photos are always welcomed.
While you are here, you may wish to complete the geocaching challenge - CX4848 - Ironblow photo challenge!
Additional Hints
(Decrypt)
[You must visit this location, and email me via GC profile or direct - earthcache@wallace.net.nz
DO NOT USE THE GC MESSAGE CENTRE PLEASE !
1. What is the month and year at the end of the brass plaque near the start of the airwalk platform.
2. What is the quote of 1897 about "Causing a stir".....
3. Describe the colour / colours of the walls of the open cast hole.]