Diabase

Part of speech: noun

Pronunciation: /ˈdaɪ.əˌbeɪs/

Definitions

1. A type of dark, sturdy volcanic rock composed mostly of plagioclase and pyroxene, frequently utilized in various construction applications
2. Characterized by its high density and fine-grained structure, this igneous rock is primarily made up of plagioclase and pyroxene minerals
3. A dense, dark volcanic rock that is rich in plagioclase and pyroxene, often recognized for its use in construction and architectural applications

Etymology: Diabase is named for a misreading of its own nature. The Greek "diábasis" meant "crossing over" or "passage," and in French, "diabase" was applied to this rock because it was thought to be a variety of greenstone, a rock that could be mistaken for another. The name reflects confusion rather than any feature of the stone itself. The Greek root is "diabainein," meaning "to go across," built from "dia-" (through, across) and "bainein" (to go). That same root gives English words about passage and crossing, and the rock's name is a French borrowing of the Greek term. Modern geologists use the word for a dark, fine-grained igneous rock of the same composition as basalt, with coarser crystals formed as it cooled slowly underground. Today it is a common technical term in petrology, though the Greek sense of passage has nothing to do with the stone it names.

Synonyms: basalt, gabbro