hyaloclast

English

Etymology

From hyalo- +‎ -clast.

Noun

hyaloclast (plural hyaloclasts)

1. (geology) A volcanic glass fragment formed by hot lava rapidly cooling when it encounters water or ice, causing it to shatter into small, glassy pieces.
   • 1974, Acta Geologica, volume 18, page 388:

     Hyaloclasts occur partly between the individual lava flows, partly in the vents penetrating the volcanic formations.

   • 1987, Brian J. Taylor, ‎N. F. Exon, Marine Geology, Geophysics, and Geochemistry of the Woodlark Basin-Solomon Islands (page 300)

     Suite IV represents sediment gravity flow deposits near a deep submarine vent, whereas Suite V represents a mixture of hemipelagic mud and epiclastic sand which incorporated some hyaloclasts.

Related terms

• hyaloclastite