volcanic

adjectives

relating to or produced by or consisting of volcanoes

"volcanic steam"; "volcanic islands such as Iceland"; "a volcanic cone is a conical mountain or hill built up of material from volcanic eruptions"

volcanic

is derived from

pertains to

explosively unstable

"a volcanic temper"

volcanic

is similar to

lacking stability or fixity or firmness

"unstable political conditions"; "the tower proved to be unstable in the high wind"; "an unstable world economy"

igneous rock produced by eruption and solidified on or near the earth's surface; rhyolite or andesite or basalt

"volcanic rock includes the volcanic glass obsidian"

volcanic

is similar to

of rock material; forced out while molten through cracks in the earth's surface