RocksdayAlbite vs Orthoclase
How to tell them apart
The sodium-rich plagioclase feldspar. In pegmatites it forms white platy crystals that often host tourmaline and other gems.
Photo: Rock Currier, CC BY 3.0
A potassium feldspar and one of the most common minerals in granite, where it forms the pink or cream-colored blocks.
Photo: Didier Descouens, CC BY-SA 4.0
Key differences
- Orthoclase is often pink and lacks the fine striations.
Side by side
| Property | Albite | Orthoclase |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 6–6.5 | 6 |
| Luster | Vitreous to pearly | Vitreous |
| Streak | White | White |
| Colors | White, Clear | Pink, White, Orange |
| Crystal system | Triclinic | Monoclinic |
| Specific gravity | 2.6–2.65 | 2.55–2.63 |
| Formula | NaAlSi₃O₈ | KAlSi₃O₈ |
| Found in | Minas Gerais, Brazil; Gilgit-Baltistan, Pakistan | Granites worldwide; Karlovy Vary, Czech Republic |
Properties that are the same for both are grayed out.
How to identify albite
- White, platy or bladed crystals.
- Fine parallel striations on cleavage faces.
- Hardness about 6.
Crystal system: Triclinic
Full Albite guide →How to identify orthoclase
- Blocky pink to cream crystals in granite.
- Two cleavages meeting at a right angle — flat, shiny faces.
- Hardness 6 — scratches glass with effort.
- No fine parallel striations (unlike plagioclase).
Crystal system: Monoclinic
Full Orthoclase guide →More comparisons
Could you tell them apart from a blurry close-up?
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