Comparison · Sedimentary Rocks
Graywacke vs Sandstone
Graywacke and Sandstone are easy to confuse because both are sedimentary 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 Graywacke and Sandstone
- Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead.
- Streak color differs: Graywacke leaves a gray to dark gray streak on unglazed porcelain, Sandstone leaves variable; test individual minerals.
- They overlap in gray and brown, but Graywacke also comes in green and black and Sandstone also comes in red, yellow, and white.
Graywacke vs Sandstone properties
| Property | Graywacke | Sandstone |
|---|---|---|
| Type | Sedimentary Rocks | Sedimentary Rocks |
| Mohs hardness | 6 | 6 |
| Luster | dull | dull |
| Streak | Gray to dark gray | Variable; test individual minerals |
| Transparency | opaque | opaque |
| Specific gravity | 2.55 | 2.3 |
| Crystal system | varies | varies |
| Common colors | Dark gray, Greenish gray, Brown, Black | Tan, Brown, Red, Yellow, White, Gray |
| Rarity | common | common |
| Typical specimen value | $1–$75+ | $1–$100+ |
Which is more valuable?
Sandstone is usually the more valuable of the two: a typical collector specimen runs about $15 against $10 for Graywacke, and premium Sandstone can reach $100 or more.
About Graywacke
Graywacke is a hard, dark, poorly sorted sandstone with a muddy matrix and mixed mineral or rock fragments.
About Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized mineral particles or rock fragments. Color varies based on mineral content and cementing material.
Graywacke vs Sandstone FAQ
Is Graywacke the same as Sandstone?
No. Both are sedimentary 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 Graywacke from Sandstone?
Both sit near Mohs 6, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Streak color differs: Graywacke leaves a gray to dark gray streak on unglazed porcelain, Sandstone leaves variable; test individual minerals. They overlap in gray and brown, but Graywacke also comes in green and black and Sandstone also comes in red, yellow, and white.
Which is harder, Graywacke or Sandstone?
They are about equally hard, both near Mohs 6.
Which is more valuable, Graywacke or Sandstone?
Sandstone is usually the more valuable of the two: a typical collector specimen runs about $15 against $10 for Graywacke, and premium Sandstone can reach $100 or more.
