diabase

A geologist examines a sample of diabase under a magnifying glass.

Definition

1. Noun:
   • A type of igneous rock: "diabase" refers to a dark-colored, fine-grained igneous rock composed primarily of plagioclase feldspar and pyroxene, typically found in dikes and sills. It is often used as a crushed stone in construction.

Usage Examples

• Noun:
  • The road was paved with crushed diabase, providing a durable surface. (A dark igneous rock used as aggregate.)
  • Geologists identified the dark rock in the cliff as diabase, noting its fine-grained texture. (A specific type of rock formed from magma.)

Advanced Usage

• "Diabase dike": a sheet of diabase that cuts across existing rock layers, often forming a vertical or nearly vertical intrusion.

  • The diabase dike was clearly visible cutting through the older sedimentary layers. (A geological feature where diabase intrudes into surrounding rock.)

• "Diabase sill": a horizontal sheet of diabase that is intruded between layers of sedimentary rock.

  • The diabase sill created a resistant cap on the hill, protecting it from erosion. (A flat-lying intrusion of diabase.)

Variants and Related Words

• Diabasic (adj): relating to or resembling diabase.

  • The diabasic texture of the rock indicates a specific cooling history. (Characteristic of diabase.)

• Diabase is a synonym for "dolerite" in some geological classifications, though "dolerite" is more commonly used in British contexts.

Synonyms

• Dolerite: a coarse-grained variety of diabase, often used interchangeably in British English.
• Microgabbro: a fine-grained igneous rock chemically similar to gabbro, sometimes used as a synonym for diabase.

Phrasal Verbs

Related Idioms