Amphibole Supergroup from
Coyote Peak, Humboldt County, California, USA
| Locality type: | Peak | |
| Classification | ||
|---|---|---|
| Species: | 'Amphibole Supergroup' (not an IMA approved species) | |
| Formula: | AB2C5(T8O22)W2 | |
| Comments: | Several amphibole supergroup minerals are found in the contact between inclusions (xenoliths) of lithic-wacke sandstone in an alkali-rich ultramafic diatreme. The amphiboles occurs as black, mm sized euhedral to subhedral crystals, associated with aegirine and feldspar. The amphibole compositions straddle across the Sodium-Calcium and Sodium subgroup with variable Ca, Ti and O2 content. Ferro-obertiite has been identified as the most oxy- and Ti- rich composition. Some of the compositions are difficult to normalize and name with the current nomenclature scheme, such as the composition (Na0,676K0,287)Σ0,963 (Na1,22Ca0,766Li0,012Mn0,002)Σ2 (Mg2,19Feii2,118Ti0,626Mnii0,04FeIII0,025)Σ4,999 (Si7,942Al0,041Ti0,017)Σ8 O22 (O0,969F0,57(OH)0,461)Σ2 that normalize to Na(NaCa)(Mg2FeII2Ti)Si8O22(OH,F)O, which is not charge-balanced | |
| Confirmation | ||
| Validity: | Believed Valid | |
| Data | ||
| Mineral Data: | Click here to view Amphibole Supergroup data | |
| Locality Data: | Click here to view Coyote Peak, Humboldt County, California, USA | |
| Data Identifiers | ||
| Mindat Occurrence Record ID: | 139604 | |
| Long-form Identifier: | 1:3:139604:1 | |
| GUID (UUID V4): | 0 | |
| References | ||
