If Djezet is liquid at room temperature, what keeps the djezet shard in the shape of a shard? Why doesn't it just turn into a puddle?
Magic? It's an artifact after all. You could just as easily ask why the Abysium shard isn't constantly poisoning everyone around it.
I believe that it's mentioned that a solid alloy can be made, and that the shard is constructed in such a way. Book 6 contains a chair made of such an alloy.