How to Identify Black Obsidian: Key Characteristics and Tests

Learn how to identify black obsidian by its glassy texture, sharp edges, and unique conchoidal fracture with simple tests.

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Identify black obsidian by its unique characteristics: it’s a glassy, jet-black volcanic glass with a smooth, almost mirror-like surface. It is often very sharp and breaks with a conchoidal fracture. Holding it against light may reveal subtle, streak-like patterns. To confirm, a Mohs hardness test will rank it around 5-5.5.

FAQs & Answers

  1. What is black obsidian made of? Black obsidian is a natural volcanic glass formed from rapidly cooling lava, primarily composed of silica.
  2. How can I test the hardness of black obsidian? You can perform a Mohs hardness test; black obsidian rates around 5 to 5.5 on the Mohs scale.
  3. What does conchoidal fracture mean in obsidian? Conchoidal fracture describes the smooth, curved breakage pattern obsidian exhibits, similar to the shape of a seashell.