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About CaswelliteHide

Beige, pinkish tan
Resinous, Waxy, Greasy
2½ - 3
Specific Gravity:
Named in 1894 by Albert H. Chester in honor of John Henry Caswell [December 27, 1846 New York, New York, USA - October 26, 1909 NY, NY, USA] mineralogist and petrologist at Columbia University, NY, NY, USA [1868-1877]. Caswell spent much of his life as a tea merchant and he assembled a notable mineral collection.
A variety of Grossular

A waxy to resinous material with a foliated appearance and derived from the hydrothermal alteration and replacement of hendricksite mica in the Franklin ore body, Franklin, New Jersey, USA. Both hendricksite and vesuvianite occurred intimately together and both were partly to completely replaced by grossular. Despite the intimate association of vesuvianite in caswellite replacements, the vesuvianite also exists as large masses in the matrix of the host rock and it too may be partially to completely replaced by grossular, but the essential appearance of caswellite as a tan lamellar mineral mimicking a mica is not also shown by the co-existing vesuvianite replaced by grossular.

Physical Properties of CaswelliteHide

Resinous, Waxy, Greasy
Translucent, Opaque
Beige, pinkish tan
2½ - 3 on Mohs scale
None Observed
3.54 g/cm3 (Measured)    

Chemical Properties of CaswelliteHide


Fluorescence of CaswelliteHide

Not fluorescent

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for CaswelliteHide

Reference List:
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Chester, Albert H. (1893) [Concerning Another Mineral at Franklin Furnace] Discussion. Transaction of the New York Academy of Science, 13, 97-98.
Chester, Albert H. (1894) On Caswellite, an altered Biotite, from Franklin Furnace, N. J. Quartz Crystals from Ellenville, N.Y. Transaction of the New York Academy of Science, 13, 181-185.

Internet Links for CaswelliteHide

Localities for CaswelliteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
  • New Jersey
    • Sussex Co.
      • Franklin mining district
The Minerals of Franklin and Sterling Hill, Sussex County, New Jersey
Mineral and/or Locality  
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