After the 7-hour journey on the Prospector Train from Perth to Kalgoorlie, my husband and I dumped our bags at our hotel then made our way, on foot, to The Super Pit lookout.  Unfortunately for us, the lookout has moved from the top of the western wall – and is now all the way down in the south, near Boulder.

Our route to the lookout (Google Maps)

9km later, we were there – staring in awe at the sheer scale of this humongous hole in the ground (and somewhat breathless, after that last 100m killer slope up to the viewpoint itself!).

The Super Pit

What was once known as The Golden Mile, The Super Pit (officially named the Fimiston Open Pit and managed by Kalgoorlie Consolidated Gold Mines) is an amalgamation of many smaller gold mining operations that will eventually measure 3.8km in length and reach a depth of over 500m.  It is HUGE.  Every year, 85 million tonnes of material are moved as part of pit operations, of which 12 million tonnes is gold-bearing ore…

These "dinky" trucks carry around 225 tonnes of material out of the pit on each trip!

…and it all started with the luck of the Irish in 1893.

Three Irish prospectors (Hannan, Flanagan and Shea) were on their way to Mount Youle from Coolgardie as word spread about a new gold strike.  Travelling separately from the hordes of other hopefuls, they discovered gold in the place now known as Kalgoorlie.  Little did they know that 5km to the south lay the richest square mile on earth – “The Golden Mile”.

Grade Control Drilling or possibly Blast Drilling - it's difficult to tell from up here!

It’s difficult to see from the above picture, but there are a number of red bollards laid out on the ground.  These bollards indicate areas of ground that are directly above old workings.  Yes, the old-timers were mining underground here back in the day!  For obvious safety reasons, they use remote-controlled drill rigs in these areas.  Now, that would be quite fun to try!

The Geological setting for these riches is an Archaean Greenstone Belt (2.9 – 2.6 billion years old).  The host-rock to 80% of the gold found at The Super Pit is known as “The Golden Mile Dolerite”.  During a phase of strike-slip faulting (i.e when tectonic plates try to move past each other e.g San Andreas Fault in California) hot, mineralised fluids invaded faults and fractures within the rocks.  The gold mineralisation, along with pyrite (Fool’s Gold), precipitated from these fluids in what must have been very favourable chemical conditions indeed.

The defined lodes (ore bodies) that occur in this massive gold deposit.

Satellite image of The Super Pit & the town of Kalgoorlie-Boulder

After steeling ourselves with an obligatory draught of beer (or two) in a Boulder pub, we walked the 9km back to our hotel; our geological pilgrimage completed.

Kalgoorlie-Boulder, Western Australia – August, 2011