Tuesday Voice: Coober Pedy (Part 3)

Down in the mines

By Vic Midyett

[Sequel to "Looking around the town"]

We visited one of the opal mines that are open to the public. It wasn't in use anymore, but they try real hard to sell you the opals they have in their showroom. Their income depends on allowing tourists to wander around underground looking at all the corridors the miners made when hunting the gem.
    Here is a somewhat crude map of how Australia looked 120 million years ago:

    The blue area was covered by an inland sea at that time. Yes, Australia was covered by an inland sea 120 million years ago [Wikipedia: "Great Artesian Basin"]. Prehistoric animals, fish, and shellfish like clams, squid, oysters, lobster. etc. died and fell to the bottom. Anything that had calcium in its bones over time created opals. There also had to be a certain amount of water and/or vapor trapped in and around them in order for nature to create the gem. Over the years the inland sea was covered over with lime stone and other material, creating the dry land country we now know.
    I heard of a miner who had found a complete shell, about an inch and a half large, that had enjoyed the perfect conditions [it's not the one shown top right]. Both sides of the shell were still attached, and a gorgeous multi-colored opal had formed, worth approximately $300,000. But such finds are very rare.
    I was told of another miner who, while digging out his bathroom for his underground home, found $250,000 in opal. Now, that covers the cost of a potty with the cost flowing in the right direction! This brings me to make note that all underground structures have to be designed and built from the top down. We are all used to thinking bottom up...a bit of a bind mender. That's mind bender for some. Sorry.
    The tunnel taking off to the left in the photo below is an access path to the showroom level, which was still about 50 feet below ground. Notice the steepness of the floor.

A shaft showing some horizontal rock lines where opals were found;
the dark passageway going to the left is an exit to ground level
(about 120 ft long at a severe angle)

Shirley and Anita in a disused mine in front of one of the old digging machines

Looking up an air shaft

The air shaft shown above also accommodated a bucket-and-man lift straight up to ground level. It's about 80 feet tall and 4 feet in diameter. In the top left corner of the photo you can see a somewhat horizontal patch where it is possible they found opal. Not that they would admit it. They are not forthcoming with that kind of information.

Next week: "A miner's tale"

Copyright © 2014 by Vic Midyett