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Glassy volcanic rock
Answer for the clue "Glassy volcanic rock ", 10 letters:
pitchstone
Alternative clues for the word pitchstone
Word definitions for pitchstone in dictionaries
Wikipedia
Word definitions in Wikipedia
Pitchstone is a dull black glassy volcanic rock formed when a felsic , viscous lava or magma cools quickly. It is similar to obsidian but is defined by the International Union of Geological Sciences as having a higher water content. It is a volcanic glass, ...
Wiktionary
Word definitions in Wiktionary
n. (context geology English) a natural glass, rich in microscopic crystallites, formed by the rapid cooling of lava or magma
The Collaborative International Dictionary
Word definitions in The Collaborative International Dictionary
Pitchstone \Pitch"stone`\, n. (Geol.) An igneous rock of semiglassy nature, having a luster like pitch.
WordNet
Word definitions in WordNet
n. dark acid granitic glass
Usage examples of pitchstone.
The characteristic rock is a black vitreous trachyte resembling pitchstone, but anhydrous.