RocksdayDiabase vs Norite
To tell Diabase from Norite: Diabase is finer grained.
Basalt's medium-grained cousin, formed in shallow sills and dikes.
Photo: CrankyScorpion at English Wikipedia, CC BY-SA 3.0
A gabbro in which the pyroxene is mostly orthopyroxene rather than augite. It is usually gray-brown and coarse.
Photo: Courtesy NASA/JPL-Caltech, Public domain
Key differences
- Diabase is finer grained.
Side by side
| Property | Diabase | Norite |
|---|---|---|
| Type | Igneous rock | Igneous rock |
| Mohs hardness | 6 | 6–7 |
| Luster | Granular | Granular |
| Colors | Black, Gray, Green | Gray, Black, Brown |
| Crystal system / structure | Medium-grained | Coarse-grained, orthopyroxene plus plagioclase |
| Specific gravity | 2.9–3.1 | 2.8–3.1 |
| Found in | Palisades, New Jersey; Preseli Hills, Wales | Sudbury, Ontario; Bushveld Complex, South Africa |
Properties that are the same for both are grayed out.
How to identify diabase
- Dark gray to black with small visible crystals.
- Heavy and tough.
- Lath-shaped feldspar between dark pyroxene.
Structure: Medium-grained
Full Diabase guide →How to identify norite
- Coarse dark gray to brownish rock.
- Blocky pale feldspar plus bronzy pyroxene.
- No quartz. Heavy.
Structure: Coarse-grained, orthopyroxene plus plagioclase
Full Norite guide →More comparisons
Frequently asked questions
What is the difference between diabase and norite?
Diabase is an igneous rock with a Mohs hardness of about 6 and a granular luster, usually black, gray or green. Norite is an igneous rock with a Mohs hardness of about 6–7 and a granular luster, usually gray, black or brown.
How can you tell diabase from norite?
Diabase is finer grained.
Could you tell them apart from a blurry close-up?
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