The fracture lines are much rougher than obsidian would have. Without being able to hold it for examination, I would say it's jasper (an opaque form of chalcedony) and the blue is flecks of agate or bluish white chalcedony. It will also be harder than obsidian. Kat, you've just gotta read up on the Moh's scales of hardness, most hardness tests can be performed with common household items, and tell lots about rocks. I believe your specimen here will test out at or near seven which most chalcedonies will do.