Many prehistoric people prized obsidian — volcanic glass — for its combination of beauty and utility. Its color can range from black to mahogany to red, and its conchoidal fracture means tools ...

If you’ve ever seen glass break, you’ve witnessed conchoidal fracture. ... A stone like obsidian, which is volcanic glass, is the poster child for conchoidal fracture.

Obsidian forms as lava, spewed from a volcano, quickly cools at surface temperatures. It's found all over the planet, including in the fantastical series Game of Thrones, where it's known as ...

Schumacher states that obsidian is not the only stone used, but chert, chalcedony, jasper, agate, and similar stones of conchoidal fracture. “The rock is first exposed to fire, and, after a ...

There is a chunk of black obsidian along my yard path, and the blackness is intense, especially on a rainy day. The stone is igneous and comes from a volcanic origin, spewed from the depths by a vi… ...

MR. LEWIS ABBOTT'S letter in NATURE of October 22 is almost entirely irrelevant to the subject of my communication to NATURE of September 24. In this note I dealt solely with one form of flint ...

Jennifer Yeoman and Hector Lomack, a couple in Edmonton, Alberta, stumbled upon a significant find while landscaping their front yard: a 4.6-pound obsidian core, rare in a region without volcanic ...

Obsidian forms when viscous lava cools rapidly, creating a cloudy, natural glass that’s often black. When broken, conchoidal fractures occur, ...

Obsidian hand ax made by John Murray, showcasing examples of conchoidal fracture produced while making flakes to shape it. John K. Murray.