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Basalt
A rock classification type
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About Basalt
A mafite or basaltoid containing mostly calcic plagioclase, clinopyroxene +/- olivine, orthopyroxene, foids, oxides and rarely quartz.
A general term for fine-grained, mafic (dark-colored) igneous rocks, commonly extrusive (volcanic) but locally intrusive (e.g., as dikes or pipes), composed chiefly of plagioclase and clinopyroxene; the fine-grained equivalent of gabbro. Olivine and iron-titanium oxides are very common and nepheline, orthopyroxene, or quartz may be present. Adj. basaltic.
A general term for fine-grained, mafic (dark-colored) igneous rocks, commonly extrusive (volcanic) but locally intrusive (e.g., as dikes or pipes), composed chiefly of plagioclase and clinopyroxene; the fine-grained equivalent of gabbro. Olivine and iron-titanium oxides are very common and nepheline, orthopyroxene, or quartz may be present. Adj. basaltic.
Unique Identifiers
Mindat ID:
48492
Long-form identifier:
mindat:1:1:48492:5
Similar Names
| Basilite | A synonym of 'Basiliite' |
Classification of Basalt
Basalt appears in fields 10,10* and 10’ in the QAPF diagram.
Basalt is found in field B in the TAS diagram.
Sub-divisions of Basalt
- Basalt
- Albasalt
- Alboranite
- Aphyric basalt
- Feldspar-basalt
- Labradoritic basalt
- Mijakite
- Ocean island basalts
- Pahoehoe
- Rhazite
- Sudburite
- Picritic-rock
- Picrobasalt
- Baslatite
- Alkali basalt
- Olivine basalt
- Subalkali basalt
- Low-Ti basalt
- High-Ti basalt
- High-Al ophitic basalt
- Amygdaloidal basalt
- Arapahite
- Flood basalt
- Carmeloite
- Basaltine
Mineralogy of Basalt
Essential minerals - these are minerals that are required within the classification of this rock:
| Calcic plagioclase | A petrological term for plagioclase series feldspars dominant in calcium. |
| Pyroxene | A petrological term for Pyroxene Group. |
Non-essential minerals - these minerals are common, sometimes major components, but are not always present:
| Feldspathoid | A family of rock-forming minerals consisting of aluminosilicates of sodium, potassium, or calcium and having too ... |
| Olivine | Commonly used as a synonym for a member of the Fayalite-Forsterite Series, but more generally and properly ... |
| Silica > Quartz | SiO2 |
Age distribution
Recorded ages:
Phanerozoic : 358.9 ± 0.4 Ma to 0 Ma - based on 95 recorded ages.
Sample ages:
| Sample ID | Recorded age | Geologic Time | Dating method |
|---|---|---|---|
| 1 | At least 0.0016 Ma | Holocene | |
| 2 | 0.280 ± 0.020 to 0.212 ± 0.038 Ma | Pleistocene | Ar/Ar |
| 3 | 1.39 ± 0.2 to 0.23 ± 0.26 Ma | Pleistocene | K-Ar |
| 4 | 2.3 to 0.7 Ma | Pleistocene | |
| 5 | 2.44 ± 0.14 to 1.01 ± 0.12 Ma | Pleistocene | K-Ar |
| 6 | 2.7 ± 0.9 to 1.8 Ma | Cenozoic | K-Ar |
| 7 | 4.00 ± 0.06 Ma | Pliocene | K-Ar |
| 8 | 4.8 ± 2.0 Ma | Pliocene | |
| 9 | 5.90 to 0.66 Ma | Cenozoic | Ar-Ar |
| 10 | 7.80 ± 0.20 to 3.10 ± 0.10 Ma | Neogene | K-Ar |
| 11 | 8.7 to 0.3 Ma | Cenozoic | |
| 12 | 10.9 ± 0.4 Ma | Miocene | K-Ar |
| 13 | 13 to 7 Ma | Miocene | |
| 14 | 23 to 20 Ma | Miocene | Ar-Ar, K-Ar, fission track |
| 15 | 24.9 Ma | Oligocene | K-Ar |
| 16 | 30.0 ± 0.05 to 29.3 ± 0.4 Ma | Oligocene | K-Ar |
| 17 | 52 to 3.5 Ma | Cenozoic | K-Ar |
| 18 | 64.7 ± 1.1 to 42.4 ± 2.3 Ma | Paleogene | |
| 19 | 100.5 to 66.0 Ma | Late/Upper Cretaceous | |
| 20 | 358.9 ± 0.4 to 298.9 ± 0.15 Ma | Paleozoic |
Sample references:
Chemical Analysis
Oxide wt%:
| 1 | |
|---|---|
| SiO2 | 51.49 % |
| TiO2 | 1.67 % |
| Al2O3 | 14.95 % |
| Fe2O3 | 2.29 % |
| FeO | 7.35 % |
| MnO | 0.15 % |
| MgO | 8.31 % |
| CaO | 8.52 % |
| Na2O | 3.91 % |
| K2O | 0.85 % |
| P2O5 | 0.46 % |
| Total: | 99.95 % |
Sample references:
| ID | Locality | Reference | Notes |
|---|---|---|---|
| 1 | Ocampo volcanic field, Ocampo Municipality, Coahuila, Mexico | Bulk-rock XRF analysis. |
Varieties of Basalt
| Basaltine | An obsolete term for a porphyritic or fine-grained variety of basalt. |
Common Associates
Associations Based on Photo Data:
| 60 photos of Basalt associated with Calcite | CaCO3 |
| 55 photos of Basalt associated with Native Copper | Cu |
| 45 photos of Basalt associated with Prehnite | Ca2Al2Si3O10(OH)2 |
| 33 photos of Basalt associated with Stilbite-Ca | NaCa4(Si27Al9)O72 · 28H2O |
| 32 photos of Basalt associated with Epidote | (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH) |
| 27 photos of Basalt associated with Apophyllite Group | AB4[Si8O20]X · 8H2O |
| 24 photos of Basalt associated with Quartz | SiO2 |
| 23 photos of Basalt associated with Heulandite Subgroup | (Na/Ca/K)5-6[Al8-9 Si27-28 O72] · nH2O |
| 23 photos of Basalt associated with Fluorapophyllite-(K) | KCa4(Si8O20)(F,OH) · 8H2O |
| 22 photos of Basalt associated with Stilbite Subgroup | M6-7[Al8-9Si27-28O72] · nH2O |
Internet Links for Basalt
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References for Basalt
Reference List:
El Hierro, Santa Cruz de Tenerife Province, Canary Islands, Spain