When a rock melts in the lava it produces a gas that mixes with the magma.
(a rock; melts; L:in the lava) (it; produces; a gas that mixes with the magma; T:When a rock melts in the lava) (a gas; mixes; with the magma)
a rock it a gas
melts produces mixes
L:in the lava
a gas that mixes with the magma T:When a rock melts in the lava
with the magma