RocksdayAchondrite vs Gabbro
To tell Achondrite from Gabbro: Gabbro is coarser and is a terrestrial plutonic rock.
A stony meteorite from a melted parent body, so it has no chondrules. The common ones, eucrites, look like a fine basalt and many are thought to come from the asteroid Vesta.
Photo: Claire H., CC BY-SA 2.0
A dark, coarse-grained rock made of pyroxene and plagioclase — basalt that cooled slowly underground.
Photo: Darla Sondrol, CC0
Key differences
- Gabbro is coarser and is a terrestrial plutonic rock.
Side by side
| Property | Achondrite | Gabbro |
|---|---|---|
| Type | Igneous rock | Igneous rock |
| Mohs hardness | 6–7 | 6–6.5 |
| Luster | Dull | Granular |
| Streak | White | — |
| Colors | Gray, White, Black | Black, Gray, Green |
| Crystal system / structure | Crystalline stony meteorite | Coarse-grained (phaneritic) |
| Specific gravity | 2.8–3.3 | 2.9–3.1 |
| Found in | Millbillillie, Australia; Camel Donga, Australia | Duluth Complex, Minnesota; Cuillin, Isle of Skye |
Properties that are the same for both are grayed out.
How to identify achondrite
- Fine gray crystalline rock, sometimes with a thin black fusion crust.
- No round chondrules.
- Heavier than a pumice, lighter than an iron. A magnet may tug only weakly, if metal grains are present.
Structure: Crystalline stony meteorite
Full Achondrite guide →How to identify gabbro
- Dark gray to black with visible crystals.
- Heavy.
- Little or no quartz.
- Gray plagioclase may show faint parallel lines.
Structure: Coarse-grained (phaneritic)
Full Gabbro guide →More comparisons
Frequently asked questions
What is the difference between achondrite and gabbro?
Achondrite is an igneous rock with a Mohs hardness of about 6–7 and a dull luster, usually gray, white or black. Gabbro is an igneous rock with a Mohs hardness of about 6–6.5 and a granular luster, usually black, gray or green.
How can you tell achondrite from gabbro?
Gabbro is coarser and is a terrestrial plutonic rock.
Could you tell them apart from a blurry close-up?
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