RocksdayAegirine vs Hornblende
The quickest way to tell Aegirine from Hornblende: Aegirine leaves a yellowish gray streak; Hornblende leaves gray-green.
A sodium-iron pyroxene that forms black to greenish-black prisms in rocks that are poor in silica.
Photo: Ivar Leidus, CC BY-SA 4.0
A common black amphibole and the dark specks in many granites and diorites.
Photo: Shannon Heinle, CC0
Quick tests
- Streak (rub on unglazed porcelain): Aegirine leaves a yellowish gray streak; Hornblende leaves gray-green.
Key differences
- Hornblende's cleavages meet near 56° and 124°, not 90°.
Side by side
| Property | Aegirine | Hornblende |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 6 | 5–6 |
| Luster | Vitreous | Vitreous |
| Streak | Yellowish gray | Gray-green |
| Colors | Black, Green, Brown | Black, Green, Brown |
| Crystal system | Monoclinic | Monoclinic |
| Specific gravity | 3.5–3.6 | 3–3.4 |
| Formula | NaFeSi₂O₆ | Ca₂(Mg,Fe,Al)₅(Al,Si)₈O₂₂(OH)₂ |
| Found in | Mount Malosa, Malawi; Mont Saint-Hilaire, Quebec | Granites and diorites worldwide; Amphibolites |
Properties that are the same for both are grayed out.
How to identify aegirine
- Black or dark green slender prisms.
- Two cleavages crossing at nearly 90°.
- Hardness about 6. Pale yellowish streak.
Crystal system: Monoclinic
Full Aegirine guide →How to identify hornblende
- Black to dark green elongated prisms.
- Two cleavages meeting at about 56° and 124°.
- Shiny, splintery breaks.
Crystal system: Monoclinic
Full Hornblende guide →More comparisons
Frequently asked questions
What is the difference between aegirine and hornblende?
Aegirine is a mineral (NaFeSi₂O₆) with a Mohs hardness of 6 and a vitreous luster, usually black, green or brown. Hornblende is a mineral with a Mohs hardness of 5–6 and a vitreous luster, usually black, green or brown.
How can you tell aegirine from hornblende?
Aegirine leaves a yellowish gray streak; Hornblende leaves gray-green. Hornblende's cleavages meet near 56° and 124°, not 90°.
Could you tell them apart from a blurry close-up?
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