metamorphic
Gneiss (with Granite/Pegmatite Vein)
Foliated Metamorphic Rock (Quartz-Feldspar Gneiss)
Hardness: 6-7 on Mohs scale. Color: Alternating dark green/gray mafic bands and pinkish-orange feldspar-rich granitic bands. Luster: Vitreous to dull. Texture: Medium to coarse-grained with distinct foliation/banding.
- Hardness
- 6-7 on Mohs scale
- Luster
- Vitreous to dull
Identified More metamorphic →
Explore Gneiss (with Granite/Pegmatite Vein) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 on Mohs scale. Color: Alternating dark green/gray mafic bands and pinkish-orange feldspar-rich granitic bands. Luster: Vitreous to dull. Texture: Medium to coarse-grained with distinct foliation/banding.
Formation & geological history
Formed through high-grade regional metamorphism of pre-existing igneous or sedimentary rocks under intense heat and pressure deep within Earth's crust. Granitic intrusions or veining occur during or post-metamorphic deformation.
Uses & applications
Widely used as dimension stone, crushed stone for construction and road base, counter tops, and decorative landscaping stones.
Geological facts
Gneiss is one of the oldest rock types found on Earth, with some specimens like the Acasta Gneiss in Canada dated to over 4 billion years old.
Field identification & locations
Identified by its characteristic alternating dark and light colored mineral bands (gneissic banding). Common in Precambrian shield areas, mountain belts, and glaciated regions. Collectors look for sharp banding contrasts.
More like this
