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Sample ML-74-49B
NavDat sample number 8393 · RHYOLITE
Sample
| Sample ID | ML-74-49B |
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| Rock name | RHYOLITE |
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| Rock type | VOLCANIC |
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| Composition | FELSIC |
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| Material | IGNEOUS |
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| Comment | Obsidian sample, rare, small <1mm phenocrysts of plagioclase An30-40 in which much of the glass has devitrified along perlitic cracks to a cryptocrystalline felsitic aggregate containing tiny feldspar microlites in a pilotaxitic arrangement. |
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Location
| Latitude | 41.6608 |
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| Longitude | -121.451 |
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| State / province | California |
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| Volcanic field | Medicine Lake Highland |
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| Location comment | 0.9 mi NE of Cougar Butte with the best outcrop located along the roadbed of the abandoned lumber railroad |
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Age
| Age (Ma) | Error | Min | Max | Geologic age | Dated by |
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| 0.43 |
|
0.39 |
0.47 |
|
|
Analyses
Whole rock
| Item | Value | Std. dev. | Unit | Method |
|---|
| SIO2 | 76.38 | | WT% | XRF |
| AL2O3 | 12.13 | | WT% | XRF |
| FEO | 0.7 | | WT% | XRF |
| FE2O3 | 0.38 | | WT% | XRF |
| TIO2 | 0.05 | | WT% | XRF |
| MNO | 0.04 | | WT% | XRF |
| MGO | 0 | | WT% | XRF |
| CAO | 0.46 | | WT% | XRF |
| NA2O | 4.46 | | WT% | XRF |
| K2O | 4.42 | | WT% | XRF |
| P2O5 | 0.01 | | WT% | XRF |
