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South shore of Big Island, Hawaii, Black Sand Beach
Provenance:
volcanic Volcanic sand of recent basaltic lava: 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.
Composition:
Composition of the sand, mineralogy, ecc. Dominantly light green volcanic glass, isotropic in polarized light. A few colourful clinopyroxen crystals (maybe olivine as well ?) and a few microlithic VRFs.
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Macroscopic view, line in |
Texture:
Texture of the grains, ecc.
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