I may not be very experienced but thats an agate/Chalcedony, actually it a cluster of several agate chalcedony, you can see the backs of them, they form the vugs, a lot of my fire agate is clustered or sandwiched like that making them very hard to carve, you have to pick which fire agate you want to keep and grind off the other fire agate, the white stuff is some kind of crust, some may be kaolinite, if you took the time with a dremel and grinded off all that crust then polished it would be a awesome specimen.