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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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Cummingtonite from
Amphibole-tourmaline-magnetite locality, Haddam Neck, Haddam, Middlesex County, Connecticut, USA


Locality type:Outcrop
Classification
Species:Cummingtonite
Formula:◻Mg2Mg5(Si8O22)(OH)2
Comments:Presence speculative. Dimorphous with anthophyllite so TEM-EDS analyses with selected area electron diffraction (SAED) to show structure was conducted on typical amphiboles in the Middletown Formation. These all proved to be anthophyllite.
Confirmation
Validity:Erroneously Reported
Data
Mineral Data:Click here to view Cummingtonite data
Locality Data:Click here to view Amphibole-tourmaline-magnetite locality, Haddam Neck, Haddam, Middlesex County, Connecticut, USA
Data Identifiers
Mindat Occurrence Record ID:920481
Long-form Identifier:1:3:920481:2
GUID (UUID V4):0
Nearest other occurrences of Cummingtonite
4.8km (3.0 miles) ⓘGarnet prospect, Middle Haddam, East Hampton, Middlesex County, Connecticut, USA
45.7km (28.4 miles) ⓘBecker Quarry, Willington, Tolland County, Connecticut, USA
92.9km (57.7 miles) ⓘChester Emery Mines, Chester, Hampden County, Massachusetts, USA
References
Schooner, Richard. (circa 1985), Untitled manuscript on central Connecticut mineralogy.
 
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