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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
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.
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
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.