Stone is a light gray material with number 5 in the Powders menu.
Stone melts at (710 C: 983 K) and turns into molten STNE. Stone itself is quite heavy.
Stone is used to simulate ground, and a simple meltable powder.
Brick turns into stone under pressure. Lava added from menu has the type of "LAVA", but it turns into stone in the same way as molten STNE. Fission reaction of plutonium creates this plain LAVA, therefore stone is created finally by the process.