📖 what
What is obsidian?
GeologyVolcanology
Quick Answer
Obsidian is volcanic glass formed when lava cools so rapidly that crystals do not have time to grow. It is usually dark and breaks with a sharp, glassy fracture.
The Full Story
Obsidian typically forms from silica-rich lava such as rhyolite that cools quickly at the surface or near it. Because it is glass rather than a crystalline rock, it can produce extremely sharp edges. Humans have used obsidian for tools and blades for thousands of years. Archaeologists often study obsidian sources to trace ancient trade routes.
Key Facts
1.natural volcanic glass
2.forms from rapid cooling of lava
3.used historically for cutting tools and blades
YouTube Angle
Suggested video title for this topic:
"The volcanic glass sharper than many metals"