Pitchstone
Usually hydrated, resinous-lustre natural volcanic glass, sometimes found in shallow intrusions or lava-related bodies.
Language and route: English calque of German Pechstein. English calque of German Pechstein
Literal gloss: pitch-like stone
The name and its history
German vernacular term; individual inventor not securely established · English term attested late eighteenth century
- What does the word literally mean?
- The immediate route is English calque of German Pechstein. In its naming context it meant ‘pitch-like stone’; deeper associations must be distinguished from the geological term's original purpose. The nineteenth-century literature uses wider glassy-rock boundaries than many modern classification schemes.
- What did the original author mean?
- An eighteenth-century English translation of the German field term Pechstein, based on its dull resinous lustre.
- Why was the name needed?
- Naturalists needed visual categories for dark glassy igneous material before mineral chemistry was routine.
- What evidence supported the original concept?
- Shiny/resinous fracture appearance and later water-content comparisons with obsidian.
- How has geology changed the concept?
- Petrographic criteria now emphasise glass texture and water content; pitchstone may form as intrusive glass, not only a lava flow.
Further historical context
An eighteenth-century English translation of the German field term Pechstein, based on its dull resinous lustre.
Naturalists needed visual categories for dark glassy igneous material before mineral chemistry was routine.
Shiny/resinous fracture appearance and later water-content comparisons with obsidian.
Petrographic criteria now emphasise glass texture and water content; pitchstone may form as intrusive glass, not only a lava flow.
Editorial qualification
The nineteenth-century literature uses wider glassy-rock boundaries than many modern classification schemes.
Related names
Sources
- 1911 Encyclopaedia Britannica, Pitchstone — Older resinous-lustre and water-content definition
- Collins Dictionary, Pitchstone — English calque of German Pechstein
- British Geological Survey, Rock Classification Scheme — Authority for modern rock categories and distinctions