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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Biotite from
Gaither's Quarry, Baltimore County, Maryland, USA


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 Gaither's Quarry, Baltimore County, Maryland, USA
Data Identifiers
Mindat Occurrence Record ID:657308
Long-form Identifier:1:3:657308:9
GUID (UUID V4):0
Nearest other occurrences of Biotite
0.7km (0.4 miles) ⓘEllicott City, Howard County, Maryland, USA
0.8km (0.5 miles) ⓘWeber's Quarry, Ellicott City, Howard County, Maryland, USA
7.9km (4.9 miles) ⓘFrost Quarry, Davis, Howard County, Maryland, USA
10.8km (6.7 miles) ⓘHilton Quarry, Baltimore City, Maryland, USA
13.8km (8.6 miles) ⓘMarriottsville Quarry, Hernwood, Baltimore County, Maryland, USA
15.3km (9.5 miles) ⓘJones Falls Quarries, Baltimore City, Maryland, USA
15.6km (9.7 miles) ⓘMcMahon Quarry (Greenspring Quarry), Pikesville, Baltimore County, Maryland, USA
16.0km (9.9 miles) ⓘWright Quarry, Stony Run, Baltimore City, Maryland, USA
16.2km (10.1 miles) ⓘStony Run, Baltimore City, Maryland, USA
18.2km (11.3 miles) ⓘStaurolite locality, Rockland, Baltimore County, Maryland, USA
References
USGS Bull. 426
 
and/or  
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