Definition

1. Noun:
   • A type of naturally occurring volcanic glass formed when lava rich in silica cools rapidly, preventing crystal growth. It is typically black or dark-colored, but can appear transparent when very thin.

Usage

• As a material: Obsidian is used for tools, weapons, and decorative objects due to its conchoidal fracture, which allows it to be shaped into sharp edges.
• In geology/archaeology: The term is used to classify a specific type of igneous rock and artifacts made from it.

Examples

• Noun:
  • The arrowhead was expertly crafted from obsidian.
  • Obsidian is often found in areas of recent volcanic activity.
  • A thin sliver of obsidian can be translucent.

Advanced Usage

• "Obsidian hydration dating": A scientific technique used in archaeology to determine the age of an obsidian artifact by measuring the microscopic layer of hydrated glass that forms on its surface over time.
  • The age of the tool was confirmed using obsidian hydration dating.

Variants and Related Words

• Obsidianite (n): A rare, naturally formed glass similar to obsidian, sometimes used as a synonym or to refer to specific varieties.
• Obsidian flow (n): A geological formation consisting of a solidified stream of obsidian-rich lava.

Synonyms

• Volcanic glass: The general category to which obsidian belongs.
• Natural glass: A broader term that includes obsidian and similar materials like fulgurites.

Related Phrases and Compounds

• Obsidian blade: A sharp cutting tool made from obsidian.
  • The surgeon used an obsidian blade for its exceptional sharpness.
• Obsidian mirror: A polished piece of obsidian used historically as a mirror or for divination.
  • The artifact was identified as an ancient obsidian mirror.

Noun

1. acid or granitic glass formed by the rapid cooling of lava without crystallization; usually dark, but transparent in thin pieces