Vote for your favorite mineral in #MinCup26! - Hafnon vs. Putnisite
It's a pair of tiny minerals of unusual chemistry as orange Hafnon battles with purple Putnisite.
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Montmorillonite from
Stockbridge Avenue occurrence, Atherton, San Mateo County, California, USA


Locality type:Occurrence
Classification
Species:Montmorillonite
Formula:(Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2 · nH2O
Confirmation
Validity:Believed Valid
Data
Mineral Data:Click here to view Montmorillonite data
Locality Data:Click here to view Stockbridge Avenue occurrence, Atherton, San Mateo County, California, USA
Data Identifiers
Mindat Occurrence Record ID:715647
Long-form Identifier:1:3:715647:2
GUID (UUID V4):0
Nearest other occurrences of Montmorillonite
2.4km (1.5 miles) ⓘSt Dennis Church parking lot, Sharon Heights, Menlo Park, San Mateo County, California, USA
2.7km (1.7 miles) ⓘSharon Park Drive, Sharon Heights, Menlo Park, San Mateo County, California, USA
2.8km (1.7 miles) ⓘSharon Park Drive outcrop, Sharon Heights, Menlo Park, San Mateo County, California, USA
3.0km (1.8 miles) ⓘSaga Foods building site, Sharon Heights, Menlo Park, San Mateo County, California, USA
3.2km (2.0 miles) ⓘSand Hill Road road cut, Sharon Heights, Menlo Park, San Mateo County, California, USA
References
Pampeyan, E.H. (2010): USGS Open-File Report 10-1053
 
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