| Locality type: | Occurrence |
| Classification |
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| Species: | Potassic-arfvedsonite |
| Formula: | [(K,Na)][Na2][Fe42+Fe3+]Si8O22(OH)2 |
| Chemical Analyses: |
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| Oxide wt%: | | 1 |
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| SiO2 | 48.63 % |
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| TiO2 | 0.43 % |
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| Al2O3 | 0.58 % |
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| MgO | 0.04 % |
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| CaO | 0.30 % |
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| MnO | 1.37 % |
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| Fe2O3 | 11.60 % |
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| FeO | 24.69 % |
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| ZnO | 0.20 % |
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| Na2O | 7.01 % |
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| K2O | 3.29 % |
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| F | 0.36 % |
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| Li2O | 0.45 % |
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| H2O | 1.7 % |
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| O=F | -0.15 % |
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| Total: | 100.5 % |
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| Empirical formulas: | | 1 | (K0.67Na0.22) 0.89(Na1.95Ca0.05) 2.00 (Fe2+ 3.29Fe3+ 1.26Li0.29Mn0.19Ti0.05Zn0.02Mg0.01) 5.11(Si7.76Fe3+ 0.13Al0.11) 8.00 O22[(OH) 1.81F0.18] 1.99 |
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| Sample references: | |
| 1 | Type Specimen | Pekov, I.V., Chukanov, N.V., Lebedeva, Yu. S., Pushcharovsky, D. Yu., Ferraris, G., Gula, A., Zadov, A.E., Novakova, A.A., Petersen, O.V. (2004) Potassicarfvedsonite, KNa2 Fe2+4Fe3+Si8O22(OH)2, a K-dominant amphibole of the arfvedsonite series from agpaitic pegmatites – Mineral data, structure refinement and disorder in the A site. Neues Jahrbuch für Mineralogie - Monatshefte, 2004 (12) 555-574 doi:10.1127/0028-3649/2004/2004-0555 |
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| Comments: | The locality of the holotype material is the “Pegmatite Valley”; the small stream in the valley being the lowermost tributary to the Lilleelv river in the Kangerluarsuk area, Southern part of Ilímaussaq complex, altitude about 260 m. Potassicarfvedsonite occurs in one or more pegmatite veinlets more than 20m long, and up to 0.5m thick, crosscutting naujaite, on both sides of the stream in the Pegmatite Valley.
The pegmatite veinlets mainly consist of white coarse-grained analcime with subordinate amounts of fine-grained sodalite, microcline, aegirine, crude crystals of steenstrupine-(Ce), eudialyte,and epistolite. Potassicarfvedsonite forms well shaped prismatic crystals from a few cm up to 15 × 0.8 cm, showing the {110} and {010} forms, included in an analcime matrix. In other parts of the veinlets, preferably the marginal parts, it occurs as mosaic individuals up to several cm in size,which combine to massive, sometimes divergent and curved, aggregates, constituting up to 30–50% of the pegmatitic rock. |
| Habit: | prismatic, showing the {110} and {010} forms |
| Colour: | Black |
| Quality for species: | Good crystals or rich for species - important (!) |
| Abundance at site: | Very common |
| Confirmation |
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| Validity: | Valid - Type Locality |
| Associated Minerals: |
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| Associates: | Analcime
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| Data |
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| Mineral Data: | Click here to view Potassic-arfvedsonite data |
| Locality Data: | Click here to view Potassic-Arfvedsonite occurrence, Pegmatite Valley, Lilleelv, Head of Kangerluarsuk, Kangerluarsuk Fjord, Ilímaussaq complex, Kujalleq, Greenland |
| Data Identifiers |
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| Mindat Occurrence Record ID: | 548965 |
| Long-form Identifier: | 1:3:548965:7 |
| GUID (UUID V4): | 754a9a27-ef72-4d99-a9f7-ffc7cd047023 |
| References |
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Pekov, I.V., Chukanov, N.V., Lebedeva, Yu. S., Pushcharovsky, D. Yu., Ferraris, G., Gula, A., Zadov, A.E., Novakova, A.A., Petersen, O.V. (2004) Potassicarfvedsonite, KNa2 Fe2+4Fe3+Si8O22(OH)2, a K-dominant amphibole of the arfvedsonite series from agpaitic pegmatites – Mineral data, structure refinement and disorder in the A site. Neues Jahrbuch für Mineralogie - Monatshefte, 2004 (12) 555-574 doi:10.1127/0028-3649/2004/2004-0555 |
Potassic-Arfvedsonite occurrence, Pegmatite Valley, Lilleelv, Head of Kangerluarsuk, Kangerluarsuk Fjord, Ilímaussaq complex, Kujalleq, Greenland