Pyroxenite
A rock classification type
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About Pyroxenite
"Pyroxenites" is the name given to ultramafic rocks comprising >60% pyroxene. The term pyroxenite (s.s.) refers to a 'true' pyroxenite containing >90% pyroxene. A coarse-grained, holocrystalline igneous rock which may contain olivine, calcic plagioclase, biotite, and/or hornblende as accessories.
Ref: CTD
Ref: CTD
Unique Identifiers
Mindat ID:
48417
Long-form identifier:
mindat:1:1:48417:4
Similar Names
| Pyroxenite (s.s.) | A rock classification type |
Classification of Pyroxenite
Modal classification of ultramafic rocks (after Streckeisen, 1973)
Sub-divisions of Pyroxenite
Mineralogy of Pyroxenite
Essential minerals - these are minerals that are required within the classification of this rock:
| Pyroxene | A petrological term for Pyroxene Group. |
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 ... |
Age distribution
Recorded ages:
Neoproterozoic to Paleogene : 773 ± 18 Ma to 66 Ma - based on 12 recorded ages.
Sample ages:
| Sample ID | Recorded age | Geologic Time | Dating method |
|---|---|---|---|
| 1 | 73 to 66 Ma | Late/Upper Cretaceous | K-Ar |
| 2 | 82.7 to 74.7 Ma | Late/Upper Cretaceous | K-Ar |
| 3 | 86.9 to 78.5 Ma | Late/Upper Cretaceous | K-Ar |
| 4 | 107.2 ± 0.8 Ma | Early/Lower Cretaceous | Ar-Ar |
| 5 | 243 ± 10 Ma | Middle Triassic | Sm-Nd isochron |
| 6 | 334 Ma | Mississippian | |
| 7 | 402 to 380 Ma | Devonian | K-Ar |
| 8 | 540 ± 39 to 521 ± 22 Ma | Terreneuvian | Sm-Nd and Rb-Sr internal isochron |
| 9 | 773 ± 18 Ma | Tonian | Rb-Sr whole rock isochron |
Sample references:
| ID | Locality | Reference | Notes |
|---|---|---|---|
| 1 | Tapira Complex, Tapira, Minas Gerais, Brazil | ||
| 2 | Serra do Salitre carbonatite, Minas Gerais, Brazil | ||
| 3 | " " | ||
| 4 | Sung Valley complex, East Khasi Hills District, Meghalaya, India | pyroxenite and 2 phlogopite separates from carbonatite | |
| 5 | Fanshan Mine, Zhuolu County, Zhangjiakou, Hebei, China | Whole rock samples and minerals | |
| 6 | Luku Complex, Yanbian County, Panzhihua, Sichuan, China | ||
| 7 | Vuoriyarvi alkaline-ultrabasic massif, Northern Karelia, Murmansk Oblast, Russia | ||
| 8 | Stjernøya Island, Alta, Troms og Finnmark, Norway | Hornblende clinopyroxenite | |
| 9 | Sevattur carbonatite complex, Krishnagiri District, Tamil Nadu, India |
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%. |
Common Associates
Associations Based on Photo Data:
| 3 photos of Pyroxenite associated with Native Platinum | Pt |
| 1 photo of Pyroxenite associated with Andradite | Ca3Fe3+2(SiO4)3 |
| 1 photo of Pyroxenite associated with 'Anorthosite' | |
| 1 photo of Pyroxenite associated with 'Pegmatite' | |
| 1 photo of Pyroxenite associated with 'Sulfide ore' | |
| 1 photo of Pyroxenite associated with Enstatite | Mg2Si2O6 |
Internet Links for Pyroxenite
mindat.org URL:
https://www.mindat.org/min-48417.html
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Gneiss quarry, Ebersdorf, Klein-Pöchlarn, Melk District, Lower Austria, Austria