RocksdayDiabase vs Lamprophyre
To tell Diabase from Lamprophyre: Diabase is a salt-and-pepper of feldspar laths and pyroxene.
Basalt's medium-grained cousin, formed in shallow sills and dikes.
Photo: CrankyScorpion at English Wikipedia, CC BY-SA 3.0
A dark dike rock whose large crystals are mica or amphibole, not feldspar.
Photo: Pelex, CC BY 3.0
Key differences
- Diabase is a salt-and-pepper of feldspar laths and pyroxene.
Side by side
| Property | Diabase | Lamprophyre |
|---|---|---|
| Type | Igneous rock | Igneous rock |
| Mohs hardness | 6 | 5–6 |
| Luster | Granular | Sparkling |
| Colors | Black, Gray, Green | Black, Gray, Green, Brown |
| Crystal system / structure | Medium-grained | Porphyritic dike rock |
| Specific gravity | 2.9–3.1 | 2.7–3 |
| Found in | Palisades, New Jersey; Preseli Hills, Wales | Vosges, France; Lake District, England |
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 lamprophyre
- Dark, with shiny black or brown flakes or needles in a fine matrix.
- Occurs as thin dikes cutting other rocks.
- The big crystals are biotite, phlogopite or amphibole.
Structure: Porphyritic dike rock
Full Lamprophyre guide →More comparisons
Frequently asked questions
What is the difference between diabase and lamprophyre?
Diabase is an igneous rock with a Mohs hardness of about 6 and a granular luster, usually black, gray or green. Lamprophyre is an igneous rock with a Mohs hardness of about 5–6 and a sparkling luster, usually black, gray, green or brown.
How can you tell diabase from lamprophyre?
Diabase is a salt-and-pepper of feldspar laths and pyroxene.
Could you tell them apart from a blurry close-up?
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