igneous
Blue Obsidian
Volcanic Glass (SiO2 with inclusions)
Hardness: 5 to 5.5 on the Mohs scale, Color: Deep vibrant blue with white inclusions, Luster: Vitreous (glassy), Crystal Structure: Amorphous (non-crystalline), Cleavage: Conchoidal fracture, Specific Gravity: 2.35 to 2.60
- Hardness
- 5 to 5
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Physical properties
Hardness: 5 to 5.5 on the Mohs scale, Color: Deep vibrant blue with white inclusions, Luster: Vitreous (glassy), Crystal Structure: Amorphous (non-crystalline), Cleavage: Conchoidal fracture, Specific Gravity: 2.35 to 2.60
Formation & geological history
Formed as an extrusive igneous rock when felsic lava cools rapidly with minimal crystal growth. Note that while natural black, brown, and mahogany obsidian are common, vibrant blue obsidian is almost exclusively man-made cullet glass or artificially colored.
Uses & applications
Used primarily in lapidary arts, decorative items, wire-wrapped jewelry, and by collectors as a striking display specimen.
Geological facts
Natural obsidian has been used since prehistoric times for making cutting tools, arrowheads, and weapons due to its extremely sharp conchoidal fracture edges.
Field identification & locations
Easily identified by its glassy luster and smooth curved conchoidal fracture surfaces. Often found in collections of lapidary materials or sold in metaphysical shops.
