Comparison · Igneous Rocks
Tonalite vs Trachyte
Tonalite and Trachyte 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 Tonalite and Trachyte
- Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Streak color differs: Tonalite leaves a white to light gray streak on unglazed porcelain, Trachyte leaves light gray to white.
- They overlap in white, gray, and green, but Tonalite also comes in black and Trachyte also comes in brown and pink.
Tonalite vs Trachyte properties
| Property | Tonalite | Trachyte |
|---|---|---|
| Type | Igneous Rocks | Igneous Rocks |
| Mohs hardness | 6 | 6 |
| Luster | dull | dull |
| Streak | White to light gray | Light gray to white |
| Transparency | opaque | opaque |
| Specific gravity | 2.75 | 2.6 |
| Crystal system | varies | varies |
| Common colors | White, Gray, Black, Salt and pepper, Greenish gray | Light gray, Tan, Pink, Brown, Greenish gray, White |
| Rarity | common | common |
| Typical specimen value | $1–$75+ | $1–$75+ |
Which is more valuable?
Typical specimens of Tonalite and Trachyte trade in a similar range, around $10.
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.
About Trachyte
Trachyte is a fine-grained volcanic rock rich in alkali feldspar. It is commonly gray, tan, pinkish, or brown and may show a rough or porphyritic texture.
Tonalite vs Trachyte FAQ
Is Tonalite the same as Trachyte?
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 Tonalite from Trachyte?
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Streak color differs: Tonalite leaves a white to light gray streak on unglazed porcelain, Trachyte leaves light gray to white. They overlap in white, gray, and green, but Tonalite also comes in black and Trachyte also comes in brown and pink.
Which is harder, Tonalite or Trachyte?
They are about equally hard, both near Mohs 6.
Which is more valuable, Tonalite or Trachyte?
Typical specimens of Tonalite and Trachyte trade in a similar range, around $10.
