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Dolerite

Medium-grained mafic shallow-intrusive rock, broadly synonymous with microgabbro in British usage.

Language and route: French dolérite from Greek dolerós. French dolérite from Greek dolerós

Literal gloss: deceptive

The name and its history

R.-J. Haüy; original naming date requires direct-source check · Not securely established

What does the word literally mean?: Literal naming sense: deceptive. Immediate language/formation: French dolérite from Greek dolerós. The epithet “deceptive” has competing detailed explanations; distinguish a documented Greek gloss from a precisely documented authorial reason.
What did the original author mean?: Haüy used the name to distinguish coarse, crystalline basaltic rocks whose appearance might lead to mistaken identification.
Why was the name needed?: Igneous rocks of intermediate cooling textures blurred the older basalt/granular-rock categories.
What evidence supported the original concept?: Hand-specimen crystal size and comparison with basaltic and dioritic rocks.
How has geology changed the concept?: It is now an emplacement/texture-related name often treated as microgabbro; in some regions diabase is a close synonym, but usages differ.

Haüy used the name to distinguish coarse, crystalline basaltic rocks whose appearance might lead to mistaken identification.

Igneous rocks of intermediate cooling textures blurred the older basalt/granular-rock categories.

Hand-specimen crystal size and comparison with basaltic and dioritic rocks.

It is now an emplacement/texture-related name often treated as microgabbro; in some regions diabase is a close synonym, but usages differ.

Haüy original wording not checked directly.

Encyclopaedia Britannica (1911), Dolerite — Historical Haüy attribution, Greek derivation and old basaltic definition
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