Comparison · Igneous Rocks
Monzonite vs Tonalite
Monzonite and Tonalite are easy to confuse because both are igneous rocks. Both sit near Mohs 6, 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 Monzonite and Tonalite
- Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Streak color differs: Monzonite leaves a variable; usually light gray streak on unglazed porcelain, Tonalite leaves white to light gray.
- They overlap in gray, white, black, and green, but Monzonite also comes in pink.
Monzonite vs Tonalite properties
| Property | Monzonite | Tonalite |
|---|---|---|
| Type | Igneous Rocks | Igneous Rocks |
| Mohs hardness | 6 | 6 |
| Luster | dull | dull |
| Streak | Variable; usually light gray | White to light gray |
| Transparency | opaque | opaque |
| Specific gravity | 2.75 | 2.75 |
| Crystal system | varies | varies |
| Common colors | Gray, Pink, White, Black, Greenish gray | 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 Monzonite and Tonalite trade in a similar range, around $10.
About Monzonite
Monzonite is a coarse-grained intrusive igneous rock with roughly balanced alkali feldspar and plagioclase and little quartz. It can resemble granite or diorite in hand sample.
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.
Monzonite vs Tonalite FAQ
Is Monzonite 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, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Monzonite from Tonalite?
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Streak color differs: Monzonite leaves a variable; usually light gray streak on unglazed porcelain, Tonalite leaves white to light gray. They overlap in gray, white, black, and green, but Monzonite also comes in pink.
Which is harder, Monzonite or Tonalite?
They are about equally hard, both near Mohs 6.
Which is more valuable, Monzonite or Tonalite?
Typical specimens of Monzonite and Tonalite trade in a similar range, around $10.
