Norite
Norite is a coarse-grained mafic intrusive igneous rock similar to gabbro but richer in orthopyroxene. It often looks dark, speckled, and dense.
Norite properties at a glance
| Type | Igneous Rocks |
|---|---|
| Chemical formula | Plagioclase and orthopyroxene-rich intrusive rock |
| Mohs hardness | 6 |
| Luster | dull |
| Streak | Gray to white |
| Cleavage | Variable by feldspar and pyroxene grains |
| Fracture | Uneven to granular |
| Specific gravity | 3 |
| Transparency | opaque |
| Common colors | Black, Dark gray, White, Greenish black, Brown |
| Rarity | common |
Geology & background
Forms when mafic magma cools slowly underground, crystallizing plagioclase with abundant orthopyroxene.
Norite helps geologists study mafic intrusions, layered igneous bodies, and deep-crust magma crystallization.
How to identify Norite
- Look for a dense, dark, coarse-grained intrusive texture.
- Pale plagioclase and dark pyroxene can create a speckled appearance.
- Norite is visually close to gabbro, so mineral details and context matter.
- Fresh surfaces are much more useful than weathered dark exteriors.
Where Norite is found
Reported from multiple igneous terrains worldwide; verify locality against specimen provenance when available.
How much is Norite worth?
| Entry-level specimen | $1 |
|---|---|
| Typical collector specimen | $10 |
| Premium specimen | $75+ |
Norite is usually valued for teaching, field context, locality, texture, color, mineral content, or unusually attractive specimens rather than high gem value.
Common uses
- Field identification
- Education
- Mafic intrusion study
- Aggregate when suitable
Interesting facts
- Norite is closely related to gabbro.
- It is important in layered mafic intrusions.
- Dark pyroxene and pale plagioclase commonly give it a salt-and-pepper look.
Care & safety
Norite can vary in toughness, porosity, vesicles, glass content, and weathering depending on cooling history and mineral mix.
Avoid inhaling dust. Do not cut, grind, or polish unknown igneous rocks without eye protection and a properly rated respirator.
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