Starting at 2 p.m., Mount Vesuvius began to rain pieces of pumice—a porous volcanic rock formed when a gas-rich froth of glassy lava solidifies rapidly—that accumulated up to 2.7 meters ...

which has been created through a partial crystallization of the glass. Since it's born out of molten rock, obsidian is only found in volcanic regions of the world, including in parts of the United ...

As with other forms of obsidian, rainbow obsidian is both rock and glass. However ... which has a long history of volcanic activity. There are four mines in this region that, with a permit ...

“High levels of volcanic gas and strands of volcanic glass are among the hazards,” the NPS warned. “Eruptive activity can change at any time.” Strands of volcanic glass, known as Pele’s ...