Andesite
Intermediate-composition volcanic rock, commonly plagioclase-rich; distinguished from basalt and dacite in IUGS schemes.
Language and route: German geological name ← Andes toponym. German geological name ← Andes toponym
Literal gloss: rock named for the Andes
The name and its history
Leopold von Buch (1826); revived by J. Roth (1861) · 1826 attribution supported by Treccani historical review
- What does the word literally mean?
- The immediate route is German geological name ← Andes toponym. In its naming context it meant ‘rock named for the Andes’; deeper associations must be distinguished from the geological term's original purpose. Original 1826 text has not been collated page by page; Andes is the immediate name source, not a literal Greek gloss.
- What did the original author mean?
- Von Buch used Andes-derived nomenclature in 1826 for a subgroup of rocks formerly included under trachyte.
- Why was the name needed?
- Existing trachyte terminology obscured distinctions among feldspar-bearing volcanics from different regions.
- What evidence supported the original concept?
- Specimens and their feldspars, rather than chemical TAS analyses, supported the early distinction.
- How has geology changed the concept?
- Roth revived the name in 1861 with a modified association of oligoclase with amphibole or augite; modern chemistry further revised boundaries.
Further historical context
Von Buch used Andes-derived nomenclature in 1826 for a subgroup of rocks formerly included under trachyte.
Existing trachyte terminology obscured distinctions among feldspar-bearing volcanics from different regions.
Specimens and their feldspars, rather than chemical TAS analyses, supported the early distinction.
Roth revived the name in 1861 with a modified association of oligoclase with amphibole or augite; modern chemistry further revised boundaries.
Editorial qualification
Original 1826 text has not been collated page by page; Andes is the immediate name source, not a literal Greek gloss.
Related names
Trachyte · Dacite · Basalt · Plagioclase
Sources
- Treccani, andesite (1929) — Explicit 1826 naming by von Buch and 1861 reintroduction by Roth
- British Geological Survey, Rock Classification Scheme — Authority for modern rock categories and distinctions
- IUGS Subcommission / Le Bas et al. (1984), TAS classification of volcanic rocks — Modern chemistry-based classification and historical standardisation; not proof of each original coinage