Peridotite
A mantle-associated ultramafic plutonic rock dominated by olivine with variable pyroxene.
Language and route: French péridotite, from péridot + -ite. French péridotite, from péridot + -ite
Literal gloss: peridot-bearing rock
The name and its history
Original individual petrological coinage undetermined · Not securely established
- What does the word literally mean?
- Literal naming sense: peridot-bearing rock. Immediate language/formation: French péridotite, from péridot + -ite. Unlike QAP granites, peridotites are described with olivine–pyroxene proportions.
- What did the original author mean?
- The name generalised rocks rich in the green mineral peridot (olivine), distinguishing them from feldspar-rich plutonic rocks.
- Why was the name needed?
- Mineral-dominated ultramafic rocks needed a compositional category outside familiar granites and gabbros.
- What evidence supported the original concept?
- Visible olivine/peridot crystals and mineralogical descriptions of coarse ultramafic rocks.
- How has geology changed the concept?
- Modern peridotite is an umbrella classification including dunite, harzburgite and lherzolite; the deeper history of peridot is uncertain.
Further historical context
The name generalised rocks rich in the green mineral peridot (olivine), distinguishing them from feldspar-rich plutonic rocks.
Mineral-dominated ultramafic rocks needed a compositional category outside familiar granites and gabbros.
Visible olivine/peridot crystals and mineralogical descriptions of coarse ultramafic rocks.
Modern peridotite is an umbrella classification including dunite, harzburgite and lherzolite; the deeper history of peridot is uncertain.
Editorial qualification
The etymology of the mineral word peridot remains debated.
Related names
Olivine · Dunite · Lherzolite · Harzburgite · Gabbro
Sources
- Collins English Dictionary, peridotite — French mineral-derived formation
- 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