Posted 9/30/2014 12:34 (#4101131 - in reply to #4100777) Subject: RE: Retry found a interesting rock yesterday (Pics loaded)
North of London
Is that a cavity I see?
If it has or had a cavity it is called a Geo (I think that is correct) formed in a volcanic eruption with a bubble in the lava.
They are found often in some locations and treated like a gemstone if they are the correct kind.
There are some that have been cut open and reveal quite pretty arrays of crystalline minerals in the pocket.