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
Tregonning Hill, Breage, Cornwall, England, UK


Locality type:Hill
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 Tregonning Hill, Breage, Cornwall, England, UK
Data Identifiers
Mindat Occurrence Record ID:1906470
Long-form Identifier:1:3:1906470:9
GUID (UUID V4):0
Nearest other occurrences of Biotite
10.2km (6.3 miles) ⓘTrencrom Hill, Trencrom, Ludgvan, Cornwall, England, UK
11.1km (6.9 miles) ⓘEast Wheal Grenville, Grenville United Mines, Troon, Camborne, Cornwall, England, UK
12.7km (7.9 miles) ⓘSouth Crofty Mine, Pool, Carn Brea, Cornwall, England, UK
19.9km (12.4 miles) ⓘLushington Cove, Porthtowan, St Agnes, Cornwall, England, UK
22.7km (14.1 miles) ⓘPendennis Head, Falmouth, Cornwall, England, UK
22.8km (14.2 miles) ⓘCarn Bosavern, St Just, Cornwall, England, UK
23.8km (14.8 miles) ⓘCrowns Rock, Cliff outcrops, Botallack, St Just, Cornwall, England, UK
37.5km (23.3 miles) ⓘWolf Rock, Cornwall, England, UK
40.6km (25.2 miles) ⓘDyer's Quarry, Chytane, St Enoder, Cornwall, England, UK
45.2km (28.1 miles) ⓘTrelavour Downs, St Dennis, Cornwall, England, UK
References
Penfound-Marks, Louis R. G.; Williamson, Ben J.; Rollinson, Gavyn K.; Shail, Robin K. (2026) Potassic Metasomatism of Slate Wall Rock and Polymetallic Mineralisation Associated with the Intrusion of a Quartz–Feldspar Porphyry Dyke in the Tregonning Hill Area of Southwest England. Minerals, 16 (4). 368 doi:10.3390/min16040368
 
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