mineral
Green tourmaline (likely chrome/dravite tourmaline crystals)
Tourmaline-group cyclosilicate; commonly elbaite, dravite, or chromdravite, complex borosilicate formula
AI-generated identification · may be incorrectSmall prismatic, striated crystals with strong vitreous luster and dark green to green-black color; typically trigonal, with no prominent cleavage and Mohs hardness 7–7.5. The image suggests separated or processed crystal fragments, but species-level identification requires testing.
Identified More mineral →
Explore Green tourmaline (likely chrome/dravite tourmaline crystals) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Small prismatic, striated crystals with strong vitreous luster and dark green to green-black color; typically trigonal, with no prominent cleavage and Mohs hardness 7–7.5. The image suggests separated or processed crystal fragments, but species-level identification requires testing.
Formation & geological history
Tourmaline forms in boron-rich granitic pegmatites, hydrothermal veins, and metamorphic rocks; crystals may be millions to billions of years old depending on the host deposit. Green varieties occur notably in Brazil, Afghanistan, Pakistan, Madagascar, Namibia, and parts of the United States.
Uses & applications
Gem-quality material is cut for jewelry; lesser crystals are collectible specimens and sources of tourmaline for geological and scientific study. Fine transparent green crystals can be valuable.
Geological facts
Tourmaline is strongly pleochroic and commonly develops lengthwise striations; heating or rubbing can produce electrical charge (the tourmaline effect).
Field identification & locations
Identify by elongated triangular-prismatic form, longitudinal grooves, glassy luster, hardness, and lack of cleavage; a gemological test is needed to distinguish elbaite from dravite or chromdravite. The pictured loose fragments may also be polished or cut material.
