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
Grignaschi Quarry, Cosasca, Trontano, Verbano-Cusio-Ossola Province, Piedmont, Italy


Locality type:Quarry
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 Grignaschi Quarry, Cosasca, Trontano, Verbano-Cusio-Ossola Province, Piedmont, Italy
Data Identifiers
Mindat Occurrence Record ID:995776
Long-form Identifier:1:3:995776:3
GUID (UUID V4):0
Nearest other occurrences of Opal
2.8km (1.8 miles) ⓘRio Graia, Trontano, Verbano-Cusio-Ossola Province, Piedmont, Italy
7.4km (4.6 miles) ⓘI Mondei (Ca' Mondei), Montescheno, Verbano-Cusio-Ossola Province, Piedmont, Italy
11.0km (6.8 miles) ⓘRencio quarries, Crodo gneiss quarries, Crodo, Verbano-Cusio-Ossola Province, Piedmont, Italy
13.5km (8.4 miles) ⓘNibbio-Val Faera (Nibbio-Val Fredda) pegmatites, Nibbio, Mergozzo, Verbano-Cusio-Ossola Province, Piedmont, Italy
14.7km (9.1 miles) ⓘEglio, Craveggia, Verbano-Cusio-Ossola Province, Piedmont, Italy
15.6km (9.7 miles) ⓘPiano del Lavonchio (Piano dei Lavonchi), Rio Vasca, Craveggia, Verbano-Cusio-Ossola Province, Piedmont, Italy
16.3km (10.1 miles) ⓘVerampio-Crego area, Premia, Verbano-Cusio-Ossola Province, Piedmont, Italy
21.6km (13.4 miles) ⓘMont'Orfano (Montorfano), Mergozzo, Verbano-Cusio-Ossola Province, Piedmont, Italy
24.4km (15.2 miles) ⓘGischi glacier (incl. Gischihorn), Binn, Goms, Valais, Switzerland
24.9km (15.5 miles) ⓘSeula mine, Mount Camoscio, Oltrefiume, Baveno, Verbano-Cusio-Ossola Province, Piedmont, Italy
References
De Michele, V. (1974) Guida mineralogica d'Italia. Istituto Geografico De Agostini.
 
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