Boulder opal is my favorite stone - bar none.  I have some others that I like a lot but none as much as boulder opal.  Boulder opal is only mined in one area of Australia and is basically opal that has grown into cracks and crevices of larger rocks, often iron or just plain stone.

A gem buyer friend of mine said it is going to get harder and harder to get so I had to buy some extra.  I find that it is really hard to photograph, so I gave it its best chance of showing you how pretty it is by getting it wet and putting it in the direct sun (which we have had very little of for the last few days).  When it is wet and in the sun it looks a whole lot like it will when it is finished.

Here are all my pieces:

Here are the best ones - can't you just see little universes and worlds in each of those little rivers of opal?