Tuffisite in obsidian

Description

Tuffisite (pink) is formed in obsidian lava (black) when the pressure of hot gas in the lava flow breaks the obsidian briefly and the gas and some ash is vented-out. The cracks rapidly anneal after the gas pressure is released and trap some of the ash that then welds to form a thin pink veneer on the obsidian. The thin tuffisite layers are then pulled-apart and disturbed as the obsidian lava continues to flow. See: https://www.frontiersin.org/articles/10.3389/feart.2016.00041/full