They say the heat and the flies here can drive a man insane. But you don't have to believe that, and nor does that bright mauve elephant that just cycled past.

Strangely enough, the madman in the hole was the only person currently on the continent who might throw any kind of light on a small drama being enacted a thousand miles away and several metres below, where the opal miner known only to his mates as Strewth was about to make the most valuable yet dangerous discovery of his career.

Strewth's pick knocked aside the rock and dust of millennia, and something gleamed in the candlelight.

It was green, like frosty green fire.

Carefully, his mind suddenly as frozen as the light under his fingers, he picked away at the loose rock. The opal picked up and reflected more and more light on to his face as the debris fell away. There seemed to be no end to the glow.

Finally, he let his breath out in one go.

'Strewth!'

If he'd found a little piece of green opal, say about the size of a bean, he'd have called his mates over and they'd have knocked off for a few beers. A piece the size of his fist would have had him pounding the floor. But with this... He was still standing there, brushing it gently with his fingers, when the other miners noticed the light and hurried over.

At least... they started out hurrying. As they came closer, they slowed to a kind of reverential walk.

No one said anything for a moment. The green light shone on their faces.

Then one of the men whispered: 'Good on yer, Strewth.'

There isn't enough money in all the world, mate.'

'Watch out, it might just be a glaze...'