17K views · 639 reactions | Up to 2.5 MILLION years ago, this OBSIDIAN was spewed forth by a volcano in a display of raw power. #volcano #geology #thecrystalcollector #Utah #obsidian | The Crystal Collector | Facebook

Obsidian is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Obsidian is produced from felsic lava, rich in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. It is commonly found within the margins of rhyolitic lava flows known as obsidian flows. These flows have a high content of silica, giving them a high viscosity. The high viscosity inhibits diffusion of atoms through