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Hungry Hill, Guilford, New Haven Co., Connecticut, USA



Detailed Mineral List:
Biotite
Reference: Harold Moritz
Cordierite
Formula: (Mg,Fe)2Al3(AlSi5O18)
Habit: anhedral to stubby subhedral, prismatic
Colour: violet, smoky blue, deep blue to light blue; dichroic
Fluorescence: none
Description: In a biotite, quartz, and plagioclase gneiss. Crystals to several cm, best formed in quartz-rich zones. Some gems have been cut from this material - see gem display at the American Museum of Natural History in New York City.
Reference: Januzzi, 1976. Mineral Localities of CT and Southeastern NY State; Rocks & Minerals (1995) 70:396-409; Hovey (1888)
Photo: © 2008 J. Zolan. Cordierite from Hungry Hill, Guilford, New Haven Co., Connecticut, USA
'Garnet'
Formula: X3Z2(SiO4)3
Habit: anhedral to subhedral
Colour: yellowish red, deep red
Fluorescence: none
Description: Two types of garnets were reported by Hovey (1888): massive yellowish red garnets associated with vesuvianite and subhedral partly gemmy, deep red garnets elsewhere in the gneiss.
Reference: Foye, 1949. The Geology of Eastern CT, p.83.; Hovey (1888)
Sillimanite
Formula: Al2(SiO4)O
Habit: acicular
Colour: white
Description: As inclusions in the cordierite according to Hovey (1888).
Reference: ex- Neil Wintringham collection (No. 399-1); Hovey (1888)
Photo: © 2009 Peter Cristofono. Sillimanite from Hungry Hill, Guilford, New Haven Co., Connecticut, USA
Vesuvianite
Formula: (Ca,Na,☐)19(Al,Mg,Fe3+)13(☐,B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10
Habit: anhedral to subhedral prismatic
Colour: dark green
Description: Associated with the yellowish red garnet in hornblende schist and gneiss
Reference: Foye, 1949. The Geology of Eastern CT, p.83; Hovey (1888).


5 entries listed. 3 valid minerals.

References

Hovey, E. O. (1888): A Cordierite Gneiss from Connecticut. American Journal of Science, Third Series, Vol. 36, No. 211, pp. 57-58.

Foye, W. G. (1949): The Geology of Eastern Connecticut. Connecticut Geological and Natural History Survey Bulletin 74, p.83.

Januzzi, Ronald E. (1976): Mineral Localities of Connecticut and Southeastern New York State. (Taylor Assoc./Mineralogical Press).

Ryerson, Kathleen. (1976): Rock Hound's Guide to Connecticut. Pequot Press.

Weber, Marcelle H. and Earle C. Sullivan. (1995): Connecticut Mineral Locality Index. Rocks & Minerals (Connecticut Issue), Vol. 70, No. 6, p. 403.

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