RocksdayAquamarine vs Phosphophyllite
The quickest way to tell Aquamarine from Phosphophyllite: Aquamarine scratches glass (Mohs 7.5–8); Phosphophyllite can't (Mohs 3–3.5).
Pale blue to sea-green beryl, often growing as clean, long hexagonal crystals.
Photo: Gunnar Ries Amphibol, CC BY-SA 2.5
A rare blue-green zinc-iron phosphate. Almost all fine crystals came from one mine in Potosí, Bolivia.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Quick tests
- Scratch glass: Aquamarine scratches glass (Mohs 7.5–8); Phosphophyllite can't (Mohs 3–3.5).
Key differences
- Aquamarine is much harder and is beryl.
Side by side
| Property | Aquamarine | Phosphophyllite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 7.5–8 | 3–3.5 |
| Luster | Vitreous | Vitreous |
| Streak | White | White |
| Colors | Blue, Green | Green, Blue |
| Crystal system | Hexagonal | Monoclinic |
| Specific gravity | 2.66–2.8 | 3.08–3.1 |
| Formula | Be₃Al₂Si₆O₁₈ (with Fe) | Zn₂Fe(PO₄)₂·4H₂O |
| Found in | Minas Gerais, Brazil; Shigar Valley, Pakistan | Potosí, Bolivia |
Properties that are the same for both are grayed out.
How to identify aquamarine
- Sea-blue, glassy six-sided prisms.
- Hardness 7.5–8.
- Often very clean and transparent.
Crystal system: Hexagonal
Full Aquamarine guide →How to identify phosphophyllite
- Blue-green transparent blades.
- Hardness only 3–3.5, with a perfect cleavage.
- A knife scratches it easily.
Crystal system: Monoclinic
Full Phosphophyllite guide →More comparisons
Frequently asked questions
What is the difference between aquamarine and phosphophyllite?
Aquamarine is a mineral with a Mohs hardness of 7.5–8 and a vitreous luster, usually blue or green. Phosphophyllite is a mineral with a Mohs hardness of 3–3.5 and a vitreous luster, usually green or blue.
How can you tell aquamarine from phosphophyllite?
Aquamarine scratches glass (Mohs 7.5–8); Phosphophyllite can't (Mohs 3–3.5). Aquamarine is much harder and is beryl.
Could you tell them apart from a blurry close-up?
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