Granodiorite is a phaneritic, intrusive igneous rock similar to granite but containing more plagioclase feldspar than orthoclase. It is commonly found in large batholiths and is characterized by a salt-and-pepper appearance caused by the mixture of light-colored minerals and darker mafic components.
Is this granodiorite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch granodiorite with a known reference. Granodiorite sits at Mohs 6-7, softer than the next harder reference, harder than the previous one.
- 2Read the textureLook at a fresh break with a hand lens. Texture: Phaneritic. Grain size: Coarse-grained.
- 3Pick out the mineralsComposition: Over 20 percent quartz, with plagioclase making up 65 to 90 percent of the feldspar, plus potassium feldspar and minor muscovite and hornblende. Identify the two or three most abundant grains.
- 4Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 5Match the color rangeCompare against the expected color range: gray, white, black, speckled.
Often confused with
Granodiorite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside granodiorite
Minerals reported to co-occur with granodiorite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 6-7
- Density
- 2.65-2.75 g/cm³
- Luster
- Vitreous
- Transparency
- Opaque
- Rarity
- Common
- Uses
- Construction, Architecture, Decorative
- Host rock
- plutonic igneous
- Texture
- Phaneritic
- Grain size
- Coarse-grained
- Composition
- Over 20 percent quartz, with plagioclase making up 65 to 90 percent of the feldspar, plus potassium feldspar and minor muscovite and hornblende
Where rockhounds find granodiorite
Classic worldwide localities
- United States
- Canada
- Norway
- Scotland
- Australia
Field-hunting tip
Where it forms: plutonic igneous. If you start seeing quartz, plagioclase, potassium feldspar in float, you are in the right ground.
Common questions
How do you identify granodiorite?+
Where is granodiorite found?+
What rocks look like granodiorite?+
What minerals are found with granodiorite?+
What kind of rock does granodiorite form in?+
What is granodiorite used for?+
Find granodiorite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
