Welcome Mine EarthCache
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Welcome mine is located on the road linking Arkaroola to Paralana
Hot Springs. "The guys were out here from about the 1860s for about
three years - they dug a fair bit of ore out and carted it off
straight away and had it processed. They made a big profit out of
it. They didn't keep digging to find more - they got out at the
right time." [1]
Leave your vehicle at the designated car park and walk up the hill
through the historic mine. At Ground Zero, you will find an
accessible mine shaft which descends 2m and then continues a few
meters with only a slight slope. It is a pleasant place on a hot
day, as underground temperatures average over the whole year.
Besides the history, discover the geology and the texture of the
different rock plugged with minerals. Enjoy the earth colors which
are particularly rich at this place. Please take memories and
souvenirs only with your camera and leave rocks and minerals in
place for coming geocachers, as they would decompose anyway in a
different climate.
Tell-tale green colorations of copper mineralization splattered on
various outcrops about Arkaroola must have been known to the
aboriginal people since time immemorial. Not unexpectedly in this
arid climate, deeply weathered, secondary oxidized copper minerals
provide abnormally colorful and eyecatching displays. Green
malachite, apple green atacamite, dark blue azurite, sky blue
chrysocolla, red cuprite and metallic native copper occur in
varying abundance around many of the old mine workings. Red
haematite laced with green malachite appears in specular rock
textures. [2]
Not surprisingly, the search for copper goes back a long time. The
rich Burra Burra and Kapunda discoveries quickly fired the the
discovery of the Yudnamutana field in the middle of the 19th
century. During the first few years, new discoveries included such
mines as The Daly, Sir Dominic, Wheal Austin, Wheal Frost, The
Welcome and many others.The mid 1860's Great Drought greatly
curtailed activity and operations all but ceased in the fields in
1869. Thereafter, prospecting or mining has continued sporadically
but unsuccessfully right up to the present. [2]
The Adelaidean Trough was initiated almost 1000 million years ago
through where now stands the Flinders and Mount Lofty Ranges,
forming the so-called Adelaide Geosyncline. It literally grew and
extended in at least five major stages extending into the Cambrian
Period, 500 million years ago. The oldest or Willouran phase was
one of widespread downfaulting in the north and voluminous volcanic
outpourings along a north-east to south-west fissure that
originally lined up with the trend of the modern east coast of Eyre
Peninsula. A series of deep local fault valleys or graben filled
with both basaltic lavas and sediments. Early on, the sea entered
these valleys depositing limestones. Much of the volcanism was
submarine so that frothing lavas became lathed with cracks and
steam vesicles . The most likely scenario for the genesis of the
mineral deposits involves circulation of basinal fluids and ore
precipitation through neutralization by fluid-rock interaction with
the dolomitic shales hosting the mineralization. [2]
Logging:
To log this earthcache, you physically have to come to this place
and answer a few questions:
Q1: Into how many corridors splits the main shaft?
Q2: The hand-cut termite resistant mulga logs used to shore up the
shafts have stood the test of time. How many of them support the
ceiling?
Q3: List the colors of the rock!
Q4: What kind of animals live here?
Please be cautious entering the mine - you are doing so at your own
risk
References:
[1] Doug Sprigg, featuring in “Arkaroola's
mining history: Keith explores the Outback region of South
Australia”, Channel 9 South Australia Pty Ltd & WIN
Corporation Pty Ltd (2006)
[2] Reg C. Sprigg: "Arkaroola - Mount Painter in the Northern
Flinders Ranges, S.A.: The Last Billion Years" (1984) Gillingham
Printers Pty Ltd, Underdale, Australia
Further reading:
Wikipedia: “Adelaide
Geosyncline”
Ian A. Dyson:
“Geology of the eastern Willouran Ranges”, MESA
Journal 35 (2004), p. 48-56.
Brugger, J.; Ogierman, J.; Pring, A.; Waldron, H.; Kolitsch, U.:
“ "Origin of the
secondary REE-minerals at the Paratoo copper deposit near
Yunta", South Australia” Mineralogical Magazine, Volume
70, Number 6, (2006 ), p. 609-627.
Additional Hints
(Decrypt)
whfg tb gurer naq unir n ybbx!