I have a civilization that lives near an active volcano. For battle, they use the lava to their advantage, and one of their projectile weapons is a small sphere with lava inside. When thrown, it explodes on impact, splattering the lava on the surrounding area (as well as any people in the vicinity).
My question is, is there an actual material or method that could hold this lava long enough without burning the person holding it, keep the lava liquid for as long as possible, and shatters/explodes on impact? (Aerogel comes to mind, being a great insulator, but I’m not sure if it can be made into a sphere. Also I’m not sure if it can actually hold lava. The sphere is so it’s easier to carry/hold/throw.)
(The sphere does not have to last too long, as it’s one of those weapons that are quickly made then used soon after. However, if it does last a while, that is even better).