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
Hunting Hill Quarry, Rockville, Montgomery 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:Unconfirmed/Questioned
Data
Mineral Data:Click here to view Biotite data
Locality Data:Click here to view Hunting Hill Quarry, Rockville, Montgomery County, Maryland, USA
Data Identifiers
Mindat Occurrence Record ID:46589
Long-form Identifier:1:3:46589:0
GUID (UUID V4):0
Nearest other occurrences of Biotite
19.4km (12.0 miles) ⓘBingham branch, Rock Creek Park, NW Washington, District of Columbia (Washington D.C.), USA
21.5km (13.4 miles) ⓘWhite Oak, Montgomery County, Maryland, USA
22.1km (13.7 miles) ⓘRock Creek Park, NW Washington, District of Columbia (Washington D.C.), USA
24.5km (15.2 miles) ⓘBrighton Dam Road Quarry (Howard-Montgomery Quarry), Howard County, Maryland, USA
36.3km (22.5 miles) ⓘFairfax Quarry, Centreville, Culpeper Basin, Fairfax County, Virginia, USA
41.2km (25.6 miles) ⓘFrost Quarry, Davis, Howard County, Maryland, USA
42.3km (26.3 miles) ⓘWeber's Quarry, Ellicott City, Howard County, Maryland, USA
42.4km (26.4 miles) ⓘEllicott City, Howard County, Maryland, USA
42.9km (26.7 miles) ⓘGaither's Quarry, Baltimore County, Maryland, USA
43.1km (26.8 miles) ⓘVulcan Materials Company Crushed Stone Quarry (Manassas Quarry), Manassas, Prince William County, Virginia, USA
References
Bernstein, Lawrence R. (1980) Minerals of the Washington, D.C. Area - Issue 5 of Educational series, Maryland Geological Survey. Department of Natural Resources, Maryland Geological Survey. p.1-148.
 
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