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

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

The lavas comprise dark pitchstone, resembling that at Kirk Yetholm, and porphyritic and amygdaloidal andesites and basalts.

From Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" by Various

This pitchstone, as well as some purple claystone porphyry, certainly flowed in the form of streams.

From Geological Observations on South America by Darwin, Charles

There is also much imperfect rubbly pitchstone, with the interstices charged with powdery carbonate of lime apparently of contemporaneous origin.

From Geological Observations on South America by Darwin, Charles