RocksdayNepheline vs Quartz
How to tell them apart
A silica-poor 'feldspathoid' found in rocks that formed without enough silica for quartz.
Photo: Andrew Silver, USGS, Public domain
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
Key differences
- Quartz is glassier and slightly harder.
Side by side
| Property | Nepheline | Quartz |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 5.5–6 | 7 |
| Luster | Greasy to vitreous | Vitreous |
| Streak | White | White |
| Colors | Gray, White, Brown | Clear, White, Gray |
| Crystal system | Hexagonal | Trigonal |
| Specific gravity | 2.55–2.66 | 2.65 |
| Formula | (Na,K)AlSiO₄ | SiO₂ |
| Found in | Bancroft, Ontario; Kola Peninsula, Russia | Hot Springs, Arkansas; Minas Gerais, Brazil |
Properties that are the same for both are grayed out.
How to identify nepheline
- Gray, greasy-looking grains.
- Never occurs with quartz.
- Hardness about 6, poor cleavage.
Crystal system: Hexagonal
Full Nepheline guide →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 →More comparisons
Could you tell them apart from a blurry close-up?
Play today's Rocksday