Limu

Limu formed as lava entered the sea on Kilauea Volcano, Hawai`i.

Limu, or Limu o Pele (Hawaiian for "seaweed of Pele"), consists of thin flakes of basaltic glass that sometimes form when pahoehoe lava pours into the ocean. As waves wash atop exposed streams of lava, some water may become trapped and boil, resulting in delicate steam-filled bubbles of lava. Abrupt chilling and continued expansion of the delicate bubble walls form thin plates and shattered pieces of brownish-green to nearly-clear glass.