ABSTRACT
We have investigated “lava straw” stalactites that formed in recently active Kilauea lava tubes using the scanning electron microscope and electron microprobe. These straws formed from the dripping of lava from the melted roof of an active lava tube. The thin-walled straws of crystallized basalt range in diameter from 5 mm to 10 mm and up to 300 mm in length. The lava straws are mostly hollow, except where constricted and at the bottom tips. The innerwalls of hollow portions of the straw display an intricate 3-dimensional network of crystals produced as cooling basalt melt was transmitted through the straw during it’s growth. These unusual formations provide a three-dimensional perspective of basalt melt crystallization through the major solidification interval from temperatures of 1140°C to less than 1000°C. In addition, horizontal and vertical sections through solid portions of the straws allow comparison of familiar two dimensional petrographic textures of basalt with the actual three dimensional structure, thus providing new insight into intercrystalline relations.
