RocksdayJasper vs Rhyolite
How to tell them apart
Opaque, impurity-rich microcrystalline quartz. Iron oxides give the classic brick red, but jasper comes in nearly every earthy color and pattern.
Photo: Tommy from Arad, CC BY 2.0
The volcanic twin of granite — same chemistry, but erupted and cooled fast, so its crystals are tiny.
Photo: Benhoff, CC BY-SA 3.0
Quick tests
- Texture: Rhyolite is a rock — a mix of grains or minerals; Jasper is a single mineral.
Key differences
- Rhyolite often shows tiny crystals or flow bands and is a little softer and grainier.
- Jasper is harder, smoother and has no crystals.
Side by side
| Property | Jasper | Rhyolite |
|---|---|---|
| Type | Mineral | Igneous rock |
| Mohs hardness | 6.5–7 | 6–6.5 |
| Luster | Dull to waxy | Dull |
| Streak | White | — |
| Colors | Red, Brown, Yellow, Green | Pink, Gray, Brown, Red |
| Crystal system / structure | Microcrystalline quartz (chalcedony) | Fine-grained, often flow-banded |
| Specific gravity | 2.5–2.9 | 2.4–2.6 |
| Formula | SiO₂ + impurities | — |
| Found in | Oregon and Idaho; India | Yellowstone, Wyoming; Owyhee region, Oregon |
Properties that are the same for both are grayed out.
How to identify jasper
- Completely opaque, even at thin edges.
- Solid earthy colors, often red, sometimes patterned.
- Hard — scratches glass.
- Smooth, curved fracture surfaces.
Crystal system: Microcrystalline quartz (chalcedony)
Full Jasper guide →How to identify rhyolite
- Light pink, tan or gray.
- Fine-grained, often with swirling flow bands.
- May have small visible quartz or feldspar crystals.
- Lighter in color and weight than basalt.
Structure: Fine-grained, often flow-banded
Full Rhyolite guide →More comparisons
Could you tell them apart from a blurry close-up?
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