Comparison · Igneous Rocks vs Quartz Family
Dunite vs Quartz
Dunite and Quartz are easy to confuse. Both sit near Mohs 6.5–7, 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 Dunite and Quartz
- Both sit near Mohs 6.5–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Dunite feels noticeably heavier for its size (specific gravity 3.2–3.3 versus 2.65 for Quartz).
- Hold a thin edge to the light: Dunite is Opaque (translucent in thin section), Quartz is Transparent to translucent.
- They overlap in yellow and brown, but Dunite also comes in green and Quartz also comes in clear, purple, pink, black, and gray.
Dunite vs Quartz properties
| Property | Dunite | Quartz |
|---|---|---|
| Type | Igneous Rocks | Quartz Family |
| Mohs hardness | 6.5–7 | 7 |
| Luster | Vitreous (olivine grains) | Vitreous, greasy on fracture surfaces |
| Streak | — | White |
| Transparency | Opaque (translucent in thin section) | Transparent to translucent |
| Specific gravity | 3.2–3.3 | 2.65 |
| Crystal system | — | Trigonal |
| Common colors | Olive green, Yellowish green, Dark green, Brown (weathered) | Colorless, White, Purple (amethyst), Yellow (citrine), Pink (rose), Brown/black (smoky) |
| Rarity | common | common |
| Typical specimen value | $1–$75+ | $5–$250+ |
Which is more valuable?
Quartz is usually the more valuable of the two: a typical collector specimen runs about $35 against $10 for Dunite, and premium Quartz can reach $250 or more.
About Dunite
Dunite is a coarse-grained ultramafic igneous rock composed almost entirely of olivine, typically more than 90 percent, with minor chromite, pyroxene, or spinel. It represents mantle material or cumulate layers formed by the settling of olivine crystals in a magma chamber, making it one of the most direct samples of Earth's upper mantle available at the surface. Its name comes from Dun Mountain in New Zealand, where it was first described.
About Quartz
Quartz is silicon dioxide, SiO2, one of the most abundant minerals in Earth's continental crust, crystallizing in the trigonal division of the hexagonal crystal system with a hardness of 7 that makes it a standard reference point on the Mohs scale. Its six-sided prismatic crystals, often terminated by pyramidal points, are among the most recognizable crystal shapes in mineralogy. Quartz occurs in nearly every rock type and geologic setting, from granite pegmatites to sedimentary sandstones to hydrothermal veins.
Dunite vs Quartz FAQ
Is Dunite the same as Quartz?
No. Dunite is a igneous rock while Quartz is a quartz family. Both sit near Mohs 6.5–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
How can you tell Dunite from Quartz?
Both sit near Mohs 6.5–7, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Dunite feels noticeably heavier for its size (specific gravity 3.2–3.3 versus 2.65 for Quartz). Hold a thin edge to the light: Dunite is Opaque (translucent in thin section), Quartz is Transparent to translucent.
Which is harder, Dunite or Quartz?
They are about equally hard, both near Mohs 6.5–7.
Which is more valuable, Dunite or Quartz?
Quartz is usually the more valuable of the two: a typical collector specimen runs about $35 against $10 for Dunite, and premium Quartz can reach $250 or more.
