Chalcedony & Chrysocolla happy via on Flickr
what causes the inside to look bubbled like that?
It’s a habit called botryoidal. It happens a lot with minerals like hematite, smithsonite, and chrysocolla. Once I’m back on Tumblr, I’ll write up a post about it with a lot of examples in various minerals. It’s one of my favourite features for minerals to have. They can form awesome stalactites and stalagmites.