The Lost Gold

I picked a stone so precious-
A gold they said.
But unrefined i thought it was,
I threw it in the furnace;
To extract a medal so honoured.
But a coal it became,
Fragile, breaking at the slightest touch.
The precious stone was no more,
I picked another, a nut they said;
Not like the lost gold-
That burnt in the furnace,
Never to return.