Vote for your favorite mineral in #MinCup26! - Sphalerite vs. Anorthite
Both zinc ore Sphalerite and calcium plagioclase feldspar Anorthite have perfect cleavage that will split cleanly if you hit them with a hammer, but only one can claim a larger split of your votes!
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Opal from
Stenna Gwyn Mine (Stennagwyn Mine), Foxhole, St Stephen-in-Brannel, Cornwall, England, UK


Locality type:Mine
Classification
Species:Opal
Formula:SiO2 · nH2O
Confirmation
Validity:Believed Valid
Data
Mineral Data:Click here to view Opal data
Locality Data:Click here to view Stenna Gwyn Mine (Stennagwyn Mine), Foxhole, St Stephen-in-Brannel, Cornwall, England, UK
Data Identifiers
Mindat Occurrence Record ID:8252
Long-form Identifier:1:3:8252:5
GUID (UUID V4):0
Nearest other occurrences of Opal
1.3km (0.8 miles) ⓘGreat Wheal Prosper China Stone Quarry, Hendra Downs, St Dennis, Cornwall, England, UK
1.7km (1.0 miles) ⓘRostowrack China Clay Pit, Hendra Downs, St Dennis, Cornwall, England, UK
2.3km (1.5 miles) ⓘBlackpool China Clay Pit, Trewoon, St Mewan, Cornwall, England, UK
2.8km (1.7 miles) ⓘGreat Longstone China Clay Pit, Longstone Downs, St Mewan, Cornwall, England, UK
2.8km (1.8 miles) ⓘVirginia China Clay Pit, Melbur, St Stephen-in-Brannel, Cornwall, England, UK
4.0km (2.5 miles) ⓘSouth Terras Mine (Resugga & Tolgarrick Mine; Union Mine; Uranium Mine), St Stephen-in-Brannel, Cornwall, England, UK
4.4km (2.8 miles) ⓘWheal Remfry China Clay Pit, Fraddon, St Enoder, Cornwall, England, UK
4.6km (2.8 miles) ⓘGunheath China Clay Pit, Stenalees, Treverbyn, Cornwall, England, UK
4.9km (3.0 miles) ⓘGreat Wheal Prosper China Clay Pit, Trezaise (Tresayes), Roche, Cornwall, England, UK
5.3km (3.3 miles) ⓘGoonbarrow China Clay Pit, Bugle, Treverbyn, Cornwall, England, UK
References
Hall, Townshend M. (1868) The Mineralogist's Directory: or, a guide to the Principal Mineral Localities in the United Kingdom of Great Britain and Ireland. Edward Stanford.
 
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