I propose 2 new elements:

LLAV(lamp lava)

and HLav(hot lamp lava)

LLAV and HLAV conduct heat very poorly, almost as well as insulator.

LLAV turns into HLAV at an arbitrary temperature boundary.

HLAV looks like LLAV but more vibrant, even when decorated.

Both would glow and flow slowly.

HLAV floats on LLAV.