Comparison · Igneous Rocks
Granodiorite vs Tonalite
Granodiorite and Tonalite are easy to confuse because both are igneous rocks. Both sit near Mohs 6–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Granodiorite and Tonalite
- Both sit near Mohs 6–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Luster is different: Granodiorite is vitreous to dull (mixed mineral grains) while Tonalite is dull.
- Hold a thin edge to the light: Granodiorite is Opaque, Tonalite is opaque.
- They overlap in gray and white, but Granodiorite also comes in pink and Tonalite also comes in black and green.
Granodiorite vs Tonalite properties
| Property | Granodiorite | Tonalite |
|---|---|---|
| Type | Igneous Rocks | Igneous Rocks |
| Mohs hardness | 6–7 | 6 |
| Luster | Vitreous to dull (mixed mineral grains) | dull |
| Streak | — | White to light gray |
| Transparency | Opaque | opaque |
| Specific gravity | 2.65–2.73 | 2.75 |
| Crystal system | — | varies |
| Common colors | Light gray, Gray, Pinkish gray, White with dark specks | White, Gray, Black, Salt and pepper, Greenish gray |
| Rarity | common | common |
| Typical specimen value | $1–$75+ | $1–$75+ |
Which is more valuable?
Typical specimens of Granodiorite and Tonalite trade in a similar range, around $10.
About Granodiorite
Granodiorite is a coarse-grained intrusive igneous rock compositionally between granite and diorite, containing more plagioclase feldspar than orthoclase feldspar along with quartz, biotite, and hornblende. It crystallizes slowly deep underground, allowing individual mineral grains to grow large enough to see without magnification. Granodiorite makes up a substantial portion of the continental crust and forms the core of many mountain ranges worldwide, including much of the Sierra Nevada batholith.
About Tonalite
Tonalite is a coarse-grained intrusive igneous rock rich in plagioclase and quartz, with less alkali feldspar than granite. It often looks gray, white, and black speckled.
Granodiorite vs Tonalite FAQ
Is Granodiorite the same as Tonalite?
No. Both are igneous rocks, but they are distinct rock types with different hardness, streak or luster. Both sit near Mohs 6–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Granodiorite from Tonalite?
Both sit near Mohs 6–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Luster is different: Granodiorite is vitreous to dull (mixed mineral grains) while Tonalite is dull. Hold a thin edge to the light: Granodiorite is Opaque, Tonalite is opaque.
Which is harder, Granodiorite or Tonalite?
Granodiorite is harder: Mohs 6–7 against Mohs 6 for Tonalite.
Which is more valuable, Granodiorite or Tonalite?
Typical specimens of Granodiorite and Tonalite trade in a similar range, around $10.
