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
Maryland Green Marble Corporation Quarry (Cardiff Serpentine Quarry), Cardiff, Harford County, Maryland, USA


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 Maryland Green Marble Corporation Quarry (Cardiff Serpentine Quarry), Cardiff, Harford County, Maryland, USA
Data Identifiers
Mindat Occurrence Record ID:1010180
Long-form Identifier:1:3:1010180:3
GUID (UUID V4):0
Nearest other occurrences of Opal
12.9km (8.0 miles) ⓘWiant's Quarry (Weiant Quarry), Pilot, Cecil County, Maryland, USA
46.0km (28.6 miles) ⓘBare Hills Serpentine Quarry East, Bare Hills, Baltimore County, Maryland, USA
46.3km (28.8 miles) ⓘUnnamed Chromite prospects, Bare Hills, Baltimore County, Maryland, USA
52.3km (32.5 miles) ⓘDelight Quarry (Soldier's Delight Quarry; Dyer Quarry), Soldiers' Delight ridge, Delight, Baltimore County, Maryland, USA
56.0km (34.8 miles) ⓘLord Baltimore Drive Quartz occurrence area, Windsor Mill, Baltimore County, Maryland, USA
58.8km (36.5 miles) ⓘPatapsco Glen Construction Site, Woodlawn, Baltimore County, Maryland, USA
62.4km (38.8 miles) ⓘGarey Ore Bank, Anne Arundel County, Maryland, USA
73.5km (45.7 miles) ⓘDyer Quarry, Gibraltar, Birdsboro, Berks County, Pennsylvania, USA
75.2km (46.7 miles) ⓘTeeter Quarry, Cumberland Township, Adams County, Pennsylvania, USA
92.4km (57.4 miles) ⓘPaint Branch, White Oak, Montgomery County, Maryland, USA
References
Ostrander, Charles W., Price, Jr, Walter E. (1940) Minerals of Maryland. The Natural History Society of Maryland, Baltimore, Maryland, USA. 14pp.p.56
 
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