Vote for your favorite mineral in #MinCup26! - Quartz vs. Asagiite
It's a classic vs a newbie as the most common named mineral in the crust Quartz is up against an exceedingly-rare sea foam-green mineral discovered just a few years ago Asagiite.
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Biotite from
Østerådalen, Østerå, Tvedestrand, Agder, Norway


Locality type:Quarry
Classification
Species:'Biotite' (not an IMA approved species)
Formula:K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Confirmation
Validity:Believed Valid
Data
Mineral Data:Click here to view Biotite data
Locality Data:Click here to view Østerådalen, Østerå, Tvedestrand, Agder, Norway
Data Identifiers
Mindat Occurrence Record ID:1580754
Long-form Identifier:1:3:1580754:0
GUID (UUID V4):0
Nearest other occurrences of Biotite
5.1km (3.2 miles) ⓘNordre Fiane Iron Mine, Solberg iron mines, Holt, Tvedestrand, Agder, Norway
5.8km (3.6 miles) ⓘSunde bridge, Snaresund, Tvedestrand, Agder, Norway
6.0km (3.8 miles) ⓘMidtbø (Midbø), Tvedestrand, Agder, Norway
6.4km (4.0 miles) ⓘJensen's Feldspar Quarry, Holt, Tvedestrand, Agder, Norway
6.4km (4.0 miles) ⓘGangdalstjern mine, Solberg iron mines, Holt, Tvedestrand, Agder, Norway
7.9km (4.9 miles) ⓘSolbutjernane, Tvedestrand, Agder, Norway
9.1km (5.7 miles) ⓘSkuggestøl Pegmatite, Risør, Agder, Norway
10.1km (6.3 miles) ⓘHauglandsvatnet, Vegårshei, Agder, Norway
10.3km (6.4 miles) ⓘFjeld Quarry (Fjellvand Quarry), Austre Moland, Arendal, Agder, Norway
10.9km (6.8 miles) ⓘGrasås Feldspar Quarry, Austre Moland, Arendal, Agder, Norway
References
Laurs, Brendan M; Renfro, Nathan D (2017) Inclusions in Sunstone Feldspar from Norway. Journal of Gemmology, 35 (7). p.584-585.
Larsen, Alf Olav (2023) Solsteinforekomsten i Østerådalen, Tvedestrand, Agder [The sunstone locality in Østerådalen, Tvedestrand, Agder]. Norsk Mineralsymposium 2023, Stathelle. 69-73
 
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