volcanic glass

American  

noun

1. a natural glass produced when molten lava cools very rapidly; obsidian.

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volcanic glass British  

noun

1. any of several glassy volcanic igneous rocks, such as obsidian and pitchstone

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volcanic glass Scientific  

1. Natural glass produced by the cooling of molten lava too quickly to permit crystallization. Obsidian is a type of volcanic glass.

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Etymology

Origin of volcanic glass

First recorded in 1830–40

Example Sentences

One gem is thought to be a rare, 2nd Century head of the Greek hero Hercules made from obsidian, a type of volcanic glass.

From BBC

Cryptotephra are signature volcanic glass shards that can range from 80-20 microns in size, which is smaller than the diameter of a human hair.

From Science Daily

The sword, also on display in the exhibit, is a flat wooden club with a groove where razor-sharp obsidian - a type of volcanic glass - would have been wedged in.

From Reuters

In 2008, Brown University researchers revisited those lunar samples with new technology and found hydrogen inside tiny beads of volcanic glass.

From Reuters

The geochemical fingerprint of the cliff’s volcanic glass has been found all around the West, as well as in Canada.

From New York Times