Inclusion

I live in Brittany, which was millions of years ago a volcanically active area and most of the rocks are of volcanic origin. Where we are is mostly granitoids - low grade granite related to granites but not as hard or regular. Our house and garden walls are made from this material and until the introduction of modern steam power and hardened steel saws was basically impossible to work properly - you hit it until it broke into a small enough piece to move and the built with it.

Now and then though you do find different things included in the rock, and today on the beach I spotted this large glassy rock. It's presumably mostly the same ingredients as the rocks around it, but as it cooled differently it didn't form the more typical rough crystalline rock, but formed this smooth glass like rock. This one was nearly 2 metres across and pretty substantial. I've not noticed it before, but the sea has been moving a lot of sand about recently so it could have been covered in sand most of the time on our recent walk.

The fluffy one wasn't impressed and simply sniffed it, and then ran off, I don't think he even bothered to mark it..!