Coarse-grained-ultramafic-rock
A rock classification type
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About Coarse-grained-ultramafic-rock
A coarse-grained crystalline igneous rock composed mostly (>90%) of mafic minerals
Unique Identifiers
Mindat ID:
50598
Long-form identifier:
mindat:1:1:50598:1
Classification of Coarse-grained-ultramafic-rock
- Rock
- Igneous rock
- Normal crystalline igneous rock
- Coarse-grained ("plutonic") crystalline igneous rock
- Coarse-grained-ultramafic-rock
- Ultramafic-rock
- Coarse-grained-ultramafic-rock
- Coarse-grained ("plutonic") crystalline igneous rock
- Normal crystalline igneous rock
- Igneous rock

Modal classification of ultramafic rocks (after Streckeisen, 1973)

Modal classification of ultramafic rocks (after Streckeisen, 1973)
Sub-divisions of Coarse-grained-ultramafic-rock
Mineralogy of Coarse-grained-ultramafic-rock
Essential minerals - these are minerals that are required within the classification of this rock:
| Mafic minerals | A petrological term for dark, rock-forming minerals rich in magnesium and/or iron. |
Non-essential minerals - these minerals are common, sometimes major components, but are not always present:
| Amphibole > Hornblende | AnCa2(Z2+5-mZ3+m)(Si8-(n+m)Al(n+m))(OH,F,Cl)2 |
| Olivine | Commonly used as a synonym for a member of the Fayalite-Forsterite Series, but more generally and properly ... |
| Pyroxene | A petrological term for Pyroxene Group. |
Age distribution
Recorded ages:
Neoproterozoic to Quaternary : 773 ± 18 Ma to 2.588 Ma - based on 16 recorded ages.
Sample ages:
| Sample ID | Recorded age | Geologic Time | Dating method |
|---|---|---|---|
| 1 | 5.332 to 2.588 Ma | Cenozoic | |
| 2 | 73 to 66 Ma | Late/Upper Cretaceous | K-Ar |
| 3 | 82.7 to 74.7 Ma | Late/Upper Cretaceous | K-Ar |
| 4 | 86.9 to 78.5 Ma | Late/Upper Cretaceous | K-Ar |
| 5 | 107.2 ± 0.8 Ma | Early/Lower Cretaceous | Ar-Ar |
| 6 | 243 ± 10 Ma | Middle Triassic | Sm-Nd isochron |
| 7 | 274.3 ± 2.2 Ma | Cisuralian | Re-Os |
| 8 | 334 Ma | Mississippian | |
| 9 | 402 to 380 Ma | Devonian | K-Ar |
| 10 | 540 ± 39 to 521 ± 22 Ma | Terreneuvian | Sm-Nd and Rb-Sr internal isochron |
| 11 | 773 ± 18 Ma | Tonian | Rb-Sr whole rock isochron |
Sample references:
Chemical Analysis
Oxide wt%:
| 1 | |
|---|---|
| SiO2 | 41.4 % |
| Al2O3 | 8.06 % |
| TiO2 | 2.69 % |
| Fe2O3 | 2.00 % |
| FeO | 12.67 % |
| MgO | 15.32 % |
| MnO | 0.18 % |
| Na2O | 0.88 % |
| CaO | 14.98 % |
| K2O | 0.33 % |
| P2O5 | 0.08 % |
| Total: | 98.59 % |
Sample references:
| ID | Locality | Reference | Notes |
|---|---|---|---|
| 1 | Mont Royal, Montréal, Québec, Canada | Wet chemical analysis by G. Woussen and B.M.Gunn. The Fe2O3 percentage is arbitrarily set to 2%. |
Synonyms of Coarse-grained-ultramafic-rock
Internet Links for Coarse-grained-ultramafic-rock
mindat.org URL:
https://www.mindat.org/min-50598.html
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References for Coarse-grained-ultramafic-rock
Reference List:




Peridot Mesa, San Carlos, Gila County, Arizona, USA