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Atacamite from
Dyke Park, Stamford, Fairfield County, Connecticut, USA

Locality type:Park
Classification
Species:Atacamite
Formula:Cu2(OH)3Cl
Comments:Henderson (1967) reports: deep green crystals of quite variable habit up to 0.5 mm in size. The terminal planes of single crystals were generally bright, while faces in the prism zone were rounded and striated (Fig. 3). It also occurred as radiating groups and in irregular aggregates, sometimes with a single larger crystal perched on top. Druses of atacamite on vesicles were common. It was most frequently found close to or on cuprite, but occasionally appeared to be on malachite.
Identification was based on its solubility in dilute hydrochloric and nitric acids, a positive test for halogen, and negative tests for carbonate and sulfate. The atacamite showed parallel extinction and weak birefringence, the two together ruling our malachite, antlerite and brochantite. The mineral was distinguished from paratacamite by its crystal form.
On occasion, crystals corresponding to atacamite were found but with a sky blue color. These may well be pseudomorphs of rosasite after atacamite.
Habit:micro radiating clusters, aggregates, druses
Colour:deep green, sky blue
Abundance at site:Very Rare
Confirmation
Validity:Confirmed
Confirmation Methods:Wet Chemical
References
References:Henderson, William, A., Jr. (1967), A Copper Analog of Laurium, Greece. Rocks & Minerals: 42(5): 273-276.
Data
Mineral Data:Click here to view Atacamite data
Locality Data:Click here to view Dyke Park, Stamford, Fairfield County, Connecticut, USA
Photo GalleryView Gallery (2 photos)
Nearest other occurrences of Atacamite
88.4km (54.9 miles) Franklin Mine, Franklin, Franklin Mining District, Sussex Co., New Jersey, USA
 
Mineral and/or Locality  
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