eruptive

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”

of igneous rock that has solidified beneath the earth''s surface; granite or diorite or gabbro

erupting or tending to erupt

• “a geyser is an intermittently eruptive hot spring”