RocksdayQuartz vs Scapolite
How to tell them apart
The second most abundant mineral in Earth's crust. Clear crystals grow as six-sided prisms capped by a pointed termination, and quartz shows up as grains in sand, granite and countless other rocks.
Photo: Didier Descouens, CC BY-SA 4.0
A group of silicates forming square prisms in metamorphosed limestones. Some glow bright yellow under UV.
Photo: Géry PARENT, CC BY-SA 4.0
Key differences
- Quartz is harder and hexagonal.
Side by side
| Property | Quartz | Scapolite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 7 | 5.5–6 |
| Luster | Vitreous | Vitreous |
| Streak | White | White |
| Colors | Clear, White, Gray | White, Gray, Yellow, Purple |
| Crystal system | Trigonal | Tetragonal |
| Specific gravity | 2.65 | 2.5–2.78 |
| Formula | SiO₂ | (Na,Ca)₄[Al(Al,Si)Si₂O₈]₃(Cl,CO₃,SO₄) |
| Found in | Hot Springs, Arkansas; Minas Gerais, Brazil | Ontario, Canada; Madagascar |
Properties that are the same for both are grayed out.
How to identify quartz
- Scratches glass easily and can't be scratched by a steel knife.
- Six-sided prisms with pointed ends when it forms crystals.
- Breaks with curved, shell-like (conchoidal) fractures — no flat cleavage planes.
- Does not fizz in vinegar or dilute acid.
Crystal system: Trigonal
Full Quartz guide →How to identify scapolite
- Square prisms with a slightly greasy luster.
- Often fluoresces yellow under longwave UV.
- Hardness about 6.
Crystal system: Tetragonal
Full Scapolite guide →More comparisons
Could you tell them apart from a blurry close-up?
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