Obsidian

Type	Igneous Rock
Texture	Glassy
Origin	Extrusive/Volcanic
Chemical Composition	Felsic
Color	Reddish Brown mottled with black
Mineral Composition	Glass
Miscellaneous	Conchoidal Fracture
Tectonic Environment	Convergent Boundary – Andean-type subduction zones, intracontinental hot spots and rifts

Type	Igneous Rock
Texture	Glassy
Origin	Extrusive/Volcanic
Chemical Composition	Felsic
Color	Black
Mineral Composition	Glass
Miscellaneous	Conchoidal Fracture
Tectonic Environment	Convergent Boundary – Andean-type subduction zones, intracontinental hot spots and rifts