tachylite - fragile basaltic glass from the 2018 Kilauea eruption that destroyed Kapoho, Hawaii - particularly fierce large display specimen

Tachylite is a light weight and fragile basaltic volcanic glass, low in silica and with a pitchlike or resinous luster. In thin sections, tachylite is brown and translucent, with numerous crystals of magnetite.

In Hawaii, entire lava flows can be tachylite, where the rapid cooling of basaltic flows has inhibited crystal formation. It rapidly weathers to palagonite, an orange to yellow isotropic mineraloid, forming a crust on lava flows. 

This tachylite was collected from the edge of a flow channel near the Puna Geothermal Plant. Lava began to flow on May 3, 2018 from a vent in Kilauea's East Rift Zone. By May 17 lava had reached the ocean and by May 27 had overrun two geothermal wells of the Puna Geothermal Project that was producing 25% of the island's electricity. A second flow overran Kapoho on June 4 and completely filled in Kapoho Bay the next day.

Because this material is fragile, large specimens like these are unusual. Excellent for display and careful handling. Iridescent glassy surface, fiercely sharp.

Both sides  are shown.