RocksdayHornblende vs Ilvaite
The quickest way to tell Hornblende from Ilvaite: Hornblende leaves a gray-green streak; Ilvaite leaves black.
A common black amphibole and the dark specks in many granites and diorites.
Photo: Shannon Heinle, CC0
A black calcium-iron silicate with a dull metallic shine, first found on the island of Elba.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Quick tests
- Streak (rub on unglazed porcelain): Hornblende leaves a gray-green streak; Ilvaite leaves black.
Key differences
- Hornblende is lighter and has a gray-green streak, not black.
Side by side
| Property | Hornblende | Ilvaite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 5–6 | 5.5–6 |
| Luster | Vitreous | Submetallic |
| Streak | Gray-green | Black |
| Colors | Black, Green, Brown | Black |
| Crystal system | Monoclinic | Orthorhombic |
| Specific gravity | 3–3.4 | 3.8–4.1 |
| Formula | Ca₂(Mg,Fe,Al)₅(Al,Si)₈O₂₂(OH)₂ | CaFe₂FeSi₂O₇O(OH) |
| Found in | Granites and diorites worldwide; Amphibolites | Elba, Italy; Dalnegorsk, Russia |
Properties that are the same for both are grayed out.
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 →How to identify ilvaite
- Black stubby prisms, often striated.
- Black streak.
- Hardness about 5.5–6. Heavier than hornblende.
Crystal system: Orthorhombic
Full Ilvaite guide →More comparisons
Frequently asked questions
What is the difference between hornblende and ilvaite?
Hornblende is a mineral with a Mohs hardness of 5–6 and a vitreous luster, usually black, green or brown. Ilvaite is a mineral with a Mohs hardness of 5.5–6 and a submetallic luster, usually black.
How can you tell hornblende from ilvaite?
Hornblende leaves a gray-green streak; Ilvaite leaves black. Hornblende is lighter and has a gray-green streak, not black.
Could you tell them apart from a blurry close-up?
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