Drywall.

This would be highly insulative (like QRTZ) and slightly flammable (less flammable than INSL) and would emit 1 WTRV over 150C and turn into 1 CLST (like drywall crumbling) it would be the hex color F8F9F5 (very pale yellow) and it would break over 5 pressure. It would melt (if not crumble somehow) at 180C into LAVA(DRWL) and when the LAVA(DRWL) resolidifies it would very likely crumble.

It would make buildings much more realistic.

(Edit: sorry if this wasn't detailed enough I just thought I had a good idea and now Google thinks I'm an engineer for looking all that up haha)