July 9, 2025 – A glassy lava bomb from lava fountaining episode 28 of the Halema‘uma‘u Kīlauea summit eruption

During episode 28 lava fountaining on Wednesday, July 9, clasts of fluid, molten lava were ejected to heights of approximately 1000 feet (300 meters) from the vent within Halema‘uma‘u crater and deposited onto the growing tephra hill on the western side of Kaluapele (Kīlauea summit caldera). These molten clasts were quickly quenched (cooled) by the air to create shiny, glassy “bombs” that preserve their fluid form, such as the one pictured here. Despite their solid appearance on the outside, these lava bombs are extremely delicate and light, with frothy interiors full of air bubbles, and they readily crumble into small pieces. With permission from Hawai‘i Volcanoes National Park, USGS Hawaiian Volcano Observatory scientists collected samples of these fresh lava bombs and pieces for geochemical analysis. The chemical compositions of these rocks, and the mineral crystals contained within, reveal information about the magma sources and storage conditions. USGS photo by K. Wall.