Obsidian
What is Obsidian?
Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimal crystal growth. Obsidian is an amorphous material, meaning it lacks a crystalline structure. It is often found with a glassy texture and can be black, brown, or green in color, depending on the impurities present.
Optical Properties
- Refractive Index
- 1.44 - 1.51
- Birefringence
- None
- Pleochroism
- None
- Optical Character
- Isotropic
- Dispersion
- 0.010
Obsidian Market Value Calculator
Estimate the market value of Obsidian using size, quality, and finish. This preview calculator is for quick context and is not a formal appraisal.
Obsidian Localities Map
See where Obsidian is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Map preview
North ZoneCentral RidgeSouth Basin
More Images
© Kafkasmurat
© Erik Baas
Quick Facts
Physical Properties
- Color
- Black, brown, green, iridescent
- Hardness (Mohs)
- 5 - 5.5
- Density
- 2.35 - 2.6 g/cm³
- Streak
- White to gray
Chemical Properties
- Chemical Formula
- SiO2
- Elements
- Silicon, oxygen, aluminum, iron, magnesium, calcium, sodium, potassium
Also Known As
Volcanic glassApache tears
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