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
Hunting Hill Quarry, Rockville, Montgomery County, Maryland, USA


09633390017362180129580.jpg
Opal

Hunting Hill Quarry, Rockville, Montgomery County, Maryland, USA
08217070017272022422642.jpg
Opal

Hunting Hill Quarry, Rockville, Montgomery County, Maryland, USA
09633390017362180129580.jpg
Opal

Hunting Hill Quarry, Rockville, Montgomery County, Maryland, USA
08217070017272022422642.jpg
Opal

Hunting Hill Quarry, Rockville, Montgomery County, Maryland, USA
09633390017362180129580.jpg
Opal

Hunting Hill Quarry, Rockville, Montgomery County, Maryland, USA
08217070017272022422642.jpg
Opal

Hunting Hill Quarry, Rockville, Montgomery 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 Hunting Hill Quarry, Rockville, Montgomery County, Maryland, USA
Photo GalleryView Gallery (2 photos)
Data Identifiers
Mindat Occurrence Record ID:46610
Long-form Identifier:1:3:46610:9
GUID (UUID V4):0
Nearest other occurrences of Opal
21.5km (13.4 miles) ⓘWhite Oak, Montgomery County, Maryland, USA
21.6km (13.4 miles) ⓘPaint Branch, White Oak, Montgomery County, Maryland, USA
25.0km (15.6 miles) ⓘOld Goose Creek Quarry, Leesburg, Loudoun County, Virginia, USA
31.8km (19.7 miles) ⓘCentreville, Culpeper Basin, Fairfax County, Virginia, USA
36.3km (22.6 miles) ⓘBull Run Quarry, Conklin, Loudoun County, Virginia, USA
43.1km (26.8 miles) ⓘVulcan Materials Company Crushed Stone Quarry (Manassas Quarry), Manassas, Prince William County, Virginia, USA
46.5km (28.9 miles) ⓘPatapsco Glen Construction Site, Woodlawn, Baltimore County, Maryland, USA
49.4km (30.7 miles) ⓘLord Baltimore Drive Quartz occurrence area, Windsor Mill, Baltimore County, Maryland, USA
50.3km (31.2 miles) ⓘGarey Ore Bank, Anne Arundel County, Maryland, USA
52.7km (32.7 miles) ⓘDelight Quarry (Soldier's Delight Quarry; Dyer Quarry), Soldiers' Delight ridge, Delight, Baltimore County, Maryland, 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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