You are correct, opalite is glass- really, anything will hold a charge that you put to it, but it’s my personal opinion that quartz is a teeny step above glass. Though really, it’s the intention that counts, so if that’s what you’ve got and it fits your intention, go for it.

Sea glass on the other hand, I feel like it’s been through a whole different process after the human production- the sea has claimed and changed it, so it has different energy than regular glass. Hit up a sea witch, they might be able to either confirm or deny this.