pitchstone

American  

[pich-stohn] / ˈpɪtʃˌstoʊn /

noun

1. a glassy volcanic rock having a resinous luster and resembling hardened pitch.

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pitchstone British  

/ ˈpɪtʃˌstəʊn /

noun

1. a dark glassy acid volcanic rock similar in composition to granite, usually intruded as dykes, sills, etc

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Etymology

Origin of pitchstone

1775–85; translation of German Pechstein. See pitch ², stone

Example Sentences

Using four 20-in. mirrors, he focuses sunlight on powdered pitchstone in a glass laboratory tube until its water of crystallization steams off.

From Time Magazine Archive

If the base be greenstone, basalt, or pitchstone, the rock may be denominated greenstone-porphyry, pitchstone-porphyry, and so forth.

From The Student's Elements of Geology by Lyell, Charles, Sir

I strongly suspect the underlying granite has altered such beds into this pitchstone.

From More Letters of Charles Darwin — Volume 1 by Darwin, Francis, Sir

In another part of the island, there are layers of pearlstone and pitchstone, which in many respects resemble those of Ascension.

From Volcanic Islands by Darwin, Charles

In some of the jaspery layers, and in some of the black siliceous slaty bands, there were irregular seams of imperfect pitchstone, undoubtedly of metamorphic origin, and other seams of brown, crystalline limestone.

From Geological Observations on South America by Darwin, Charles