Obsidian is an extrusive igneous rock characterized by its glass-like appearance and lack of a crystalline structure. This unique rock is typically black or dark brown, but it can also be found in shades of green, red, or even with a golden sheen. Its smooth, conchoidal fracture results in sharp edges, which have been utilized for various tools and weapons since prehistoric times. Today, obsidian continues to captivate geologists, collectors, and artists alike due to its intriguing properties and aesthetic appeal.

Mineral Makeup

Obsidian’s mineral composition is primarily composed of silica (SiO2) with minor amounts of other elements such as iron and magnesium. Its glassy texture is a result of the rapid cooling of viscous lava, which inhibits the formation of a crystalline structure. As a volcanic glass, obsidian is unique among igneous rocks as it does not contain distinct mineral crystals.


Obsidian forms when lava with a high silica content cools rapidly, preventing the formation of a crystalline structure. This rapid cooling can occur when lava flows quickly across the surface or when it comes into contact with water. The glass-like texture of obsidian is a direct result of this rapid cooling process.


Obsidian can be found in volcanic regions worldwide, often near the edges of lava flows or in areas where volcanic activity has occurred in the past. Some notable locations where obsidian is found include the obsidian cliffs in Yellowstone National Park in the United States, the Obsidian Dome in California, the Hrafntinnusker plateau in Iceland, and the volcanic islands of Lipari in Italy and Santorini in Greece.


Obsidian is believed to have various metaphysical properties, including grounding, protection, and self-reflection. It is thought to help individuals connect with their inner selves and release negative emotions, promoting emotional healing and growth. Obsidian is also said to provide protection from negativity and psychic attacks, making it a popular choice for spiritual practitioners and energy workers.

ClassIgneous (Extrusive) 
Mineral MakeupPrimarily silica (SiO2) with minor amounts of other elements
Hardness (Mohs)5-6
StreakWhite or colorless 
ColorBlack, dark brown, green, red, or with a golden sheen
CleavageNone, conchoidal fracture
Specific Gravity2.3 to 2.6