0085 Black Sand Beach, Big Island, Hawaii, USA

Volcanic litharenite, Black Sand Beach, Big Island, Hawaii

Location:

South shore of Big Island, Hawaii, Black Sand Beach

Provenance:

Volcanic sand of recent basaltic lava

Composition:

Dominantly light green volcanic glass, isotropic in polarized light. A few colourful clinopyroxen crystals (maybe olivine as well ?) and a few microlithic VRFs

Petrographic thin section:

Basaltic VRFs

Texture:

A coarse-grained, moderately to poorly sorted, extremely angular volcanic sand of recent basaltic lava. The extreme angularity and the preservation of many partial bubble outlines is unusual in sands but highly diagnostic in the interpretation in sandstone provenance. Medium to coarse sand (250 to 1250 μm)

Sample Number:

heubeck0085

Collector:

Christoph Heubeck, Institut für Geologische Wissenschaften, Freie Universität Berlin

Date:

1991

Comments:

Along Hawaii's south coast, basaltic lava, up to 1100 deg C hot, is shock-cooled upon contact with the sea water. Glassy beads and highly porous basaltic "spatter" form which are quickly ground up into shards by shoreline surf and swash. The black beach becomes extremely hot under the morning sun