Comparison · Igneous Rocks
Phonolite vs Trachyte
Phonolite 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 Phonolite and Trachyte
- Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- They overlap in gray, green, brown, and white, but Phonolite also comes in black and Trachyte also comes in pink.
Phonolite vs Trachyte properties
| Property | Phonolite | Trachyte |
|---|---|---|
| Type | Igneous Rocks | Igneous Rocks |
| Mohs hardness | 6 | 6 |
| Luster | dull | dull |
| Streak | Light gray to white | Light gray to white |
| Transparency | opaque | opaque |
| Specific gravity | 2.6 | 2.6 |
| Crystal system | varies | varies |
| Common colors | Gray, Greenish gray, Brown, Black, White | Light gray, Tan, Pink, Brown, Greenish gray, White |
| Rarity | uncommon | common |
| Typical specimen value | $1–$75+ | $1–$75+ |
Which is more valuable?
Typical specimens of Phonolite and Trachyte trade in a similar range, around $10.
About Phonolite
Phonolite is an alkali-rich volcanic rock, often gray to greenish gray and fine-grained. Some pieces ring when struck, which inspired the name.
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.
Phonolite vs Trachyte FAQ
Is Phonolite 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 Phonolite from Trachyte?
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. They overlap in gray, green, brown, and white, but Phonolite also comes in black and Trachyte also comes in pink.
Which is harder, Phonolite or Trachyte?
They are about equally hard, both near Mohs 6.
Which is more valuable, Phonolite or Trachyte?
Typical specimens of Phonolite and Trachyte trade in a similar range, around $10.
