• Specimen Number

  50

• Description

  Round cobble of olivine basalt likely from a pocket beach. Voids resembling vesicles are heterogeneous and not aligned, suggesting they result from weathering of less resistant minerals. Bright green minerals in two voids are visible in the upper right portion of the close-up.  They appear to be olivine.

• Classification

  Igneous. Volcanic. Basalt. Vesicular.

• Location & Occurrence

  Unusually coarse grained for a basalt.

• Geological Age

  Likely a million years or less, depending on location.

• Geoheritage

  Hawaii has the simplest geology of any state. The islands are  mountains of lava flows being eroded by fluvial processes with the the shorelines eroded by wave action and fringed by coral.

• Links

  Link to State Geological Map from USGS.  Link to Hawaiian Volcanoes Observatory.

• Other

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