propylite

A geologist examines a sample of propylite in the field.

Definition

1. Noun (Geology, Mineralogy):
   • A hydrothermally altered andesite or similar volcanic rock: "Propylite" is a specific type of altered volcanic rock, typically formed when andesite or other intermediate volcanic rocks undergo low-grade metamorphism or hydrothermal alteration. It is characterized by the presence of minerals such as chlorite, epidote, calcite, and pyrite, often giving it a greenish or grayish colour.

Usage Examples

• Noun:
  • The geologist identified the greenish rock as propylite, noting its chlorite and epidote content. (The rock was classified as a hydrothermally altered volcanic rock.)
  • In the mining district, propylite often hosts gold and copper deposits. (The altered rock is associated with valuable minerals.)

Advanced Usage

• "Propylitic alteration": The process by which a volcanic rock is transformed into propylite through hydrothermal fluids.
  • The propylitic alteration zone indicates past volcanic activity and potential ore formation. (The alteration process marks a geological region of interest.)

Variants and Related Words

• Propylitic (adj): relating to or characteristic of propylite.
  • The propylitic minerals include chlorite and epidote. (The minerals typical of this rock type.)

Synonyms

• Altered andesite: a general term for andesite that has undergone hydrothermal change.
• Hydrothermally altered rock: a broader category that includes propylite.

Related Idioms

• None specific to "propylite" as it is a technical geological term; however, in geological contexts:
  • "Propylite zone": a region of rock exhibiting propylitic alteration.

    • The propylite zone was mapped as part of the exploration survey. (The area of altered rock was charted.)