Making useful cement products

Pubity on Instagram: "⛏️ When lava meets water, the rapid cooling causes the outer surface of the lava to harden instantly while the inside stays molten, often forming cracked, glassy rock. The extreme temperature difference can also flash the water into steam, sometimes triggering explosive reactions that shatter the lava into fragments and send steam and ash into the air, especially when lava flows into the ocean or erupts underwater. (EpicLava via ViralHog) #surprise"