Definition

1. Noun:
   • A granular crystalline intrusive rock: Diorite is a type of igneous rock that forms from the slow cooling of magma beneath the Earth's surface (making it intrusive). It has a coarse-grained, granular texture where individual mineral crystals are visible to the naked eye. Its composition is intermediate, typically containing plagioclase feldspar, amphibole, and often biotite mica, but little to no quartz.

Usage Examples

• Noun:
  • The ancient statue was carved from a block of gray diorite.
  • Geologists identified the mountain's core as being composed primarily of diorite.
  • Diorite is often used as a decorative stone in construction due to its attractive speckled appearance.

Advanced Usage

• Petrological Context: In geology, "diorite" is classified based on its mineral content, specifically when the plagioclase feldspar is more sodium-rich (andesine). A variant with more calcium-rich plagioclase is called "gabbro."
• Historical/Archaeological Context: Diorite was highly valued in antiquity for its hardness and durability, used for tools, stelae, and sculpture.
  • The Code of Hammurabi is inscribed on a black diorite stele.

Variants and Related Words

• Dioritic (adj): Having the properties of or relating to diorite.
  • The dioritic intrusion created a distinct geological feature.
• Quartz Diorite (n): A type of diorite containing a significant amount of quartz, transitional to granodiorite.

Synonyms

• Intermediate intrusive rock: A broader category describing igneous rocks with a chemical composition between felsic (like granite) and mafic (like gabbro).

Related Terms (Not Phrasal Verbs or Idioms)

• Plutonic rock: A synonym for intrusive igneous rock, named after Pluto, the Roman god of the underworld, referencing its deep-seated formation.
• Andesite: The volcanic (extrusive) equivalent of diorite, which has a similar chemical composition but a finer-grained texture due to rapid cooling at the surface.

Noun

1. a granular crystalline intrusive rock