Gabbro
Coarse-grained mafic plutonic rock rich in calcic plagioclase and pyroxene, sometimes olivine.
Language and route: Italian/Tuscan stoneworking and regional geological word. Italian/Tuscan stoneworking and regional geological word
Literal gloss: opaque; locality or dialect word
The name and its history
Leopold von Buch (1809) petrographic usage; earlier regional and stoneworker use · 1809 geological application (secondary attestation)
- What does the word literally mean?
- Literal naming sense: opaque; locality or dialect word. Immediate language/formation: Italian/Tuscan stoneworking and regional geological word. Gabbro is also a Tuscan place-name; a precise single derivational route is unresolved.
- What did the original author mean?
- Italian marble-workers and early geologists used gabbro for Tuscan Apennine rocks, including material now understood as altered or metamorphosed.
- Why was the name needed?
- Early mapping of the ophiolitic rocks required field terms for dark rocks that were not adequately separated mineralogically.
- What evidence supported the original concept?
- Quarrying and field associations near Tuscan settlements, followed by improved petrographic analyses.
- How has geology changed the concept?
- Present gabbro is a modal/compositional class of plutonic rock. Earlier Italian gabbro need not meet this definition.
Further historical context
Italian marble-workers and early geologists used gabbro for Tuscan Apennine rocks, including material now understood as altered or metamorphosed.
Early mapping of the ophiolitic rocks required field terms for dark rocks that were not adequately separated mineralogically.
Quarrying and field associations near Tuscan settlements, followed by improved petrographic analyses.
Present gabbro is a modal/compositional class of plutonic rock. Earlier Italian gabbro need not meet this definition.
Editorial qualification
The proposed Latin glaber derivation is conjectural.
Related names
Diorite · Norite · Anorthosite · Dolerite · Peridotite · QAPF classification
Sources
- Online Etymology Dictionary, gabbro — Tuscan quarry vocabulary, von Buch 1809 and uncertain deeper origin
- BGS, Rock Classification Scheme — Modern descriptive rock-naming principles and definitions
- USGS, Lithologic classification of geologic map units — Modal definitions and named plutonic-rock categories
- IUGS / Le Maitre et al. (2002), Igneous Rocks: A Classification and Glossary of Terms, ch. 3 — Authoritative IUGS rock-name history and bibliographic attributions