Yea, it shares the name, is black, and crystalline. It might be something completely different, or it might be the same thing; but it does share a lot of features. Ultimately, we don't know what different types of states it exists under in Novia. There might be some states under which it shatters easily, and others where its hard. It might even be in that case that its fragile state might be the one in which ether is absent; and that would make it like obsidian on Earth. Its harder state might be the one in which ether is present; and that might account for the strength of obsidian on Novia. Its all speculation, yes.