BOULDER MAGIC
PIPE OPAL
This is a natural pipe opal. This material has some sand and or vegetation in the back ground. As the sand is hard to polish this has been stabilized.
This crystal opal is from unique pipe like structure that is usually formed in sandstone and not ironstone. There may be some sand inclusions in the stone which is natural as that is how they have formed. The pipes may be several centimeters in diameter and can be hollow or opal filled. They can be found in knotted masses. There formation is possibly joint controlled or they may be from zones high permeability with in the sand stone that acted as a channel for water flow.