Comparison · Sedimentary Rocks vs Quartz Family
Arkose vs Quartz
Arkose and Quartz are easy to confuse. Quartz is harder (Mohs 7) than Arkose (Mohs 6), so Quartz will scratch Arkose and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Arkose and Quartz
- Quartz is harder (Mohs 7) than Arkose (Mohs 6), so Quartz will scratch Arkose and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
- Streak color differs: Arkose leaves a variable; usually light-colored streak on unglazed porcelain, Quartz leaves white.
- Luster is different: Arkose is dull while Quartz is vitreous, greasy on fracture surfaces.
- Hold a thin edge to the light: Arkose is opaque, Quartz is Transparent to translucent.
- They overlap in pink, brown, and gray, but Arkose also comes in red and white and Quartz also comes in clear, purple, yellow, and black.
Arkose vs Quartz properties
| Property | Arkose | Quartz |
|---|---|---|
| Type | Sedimentary Rocks | Quartz Family |
| Mohs hardness | 6 | 7 |
| Luster | dull | Vitreous, greasy on fracture surfaces |
| Streak | Variable; usually light-colored | White |
| Transparency | opaque | Transparent to translucent |
| Specific gravity | 2.45 | 2.65 |
| Crystal system | varies | Trigonal |
| Common colors | Pink, Red, Tan, Gray, White | 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 Arkose, and premium Quartz can reach $250 or more.
About Arkose
Arkose is a feldspar-rich sandstone that often looks pink, reddish, tan, or light gray and may show visible sand-sized grains.
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.
Arkose vs Quartz FAQ
Is Arkose the same as Quartz?
No. Arkose is a sedimentary rock while Quartz is a quartz family. Quartz is harder (Mohs 7) than Arkose (Mohs 6), so Quartz will scratch Arkose and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
How can you tell Arkose from Quartz?
Quartz is harder (Mohs 7) than Arkose (Mohs 6), so Quartz will scratch Arkose and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Streak color differs: Arkose leaves a variable; usually light-colored streak on unglazed porcelain, Quartz leaves white. Luster is different: Arkose is dull while Quartz is vitreous, greasy on fracture surfaces.
Which is harder, Arkose or Quartz?
Quartz is harder: Mohs 7 against Mohs 6 for Arkose.
Which is more valuable, Arkose or Quartz?
Quartz is usually the more valuable of the two: a typical collector specimen runs about $35 against $10 for Arkose, and premium Quartz can reach $250 or more.
