Hardystonite

Hardystonite is a rare purple fluorescent silicate mineral from the famous Franklin, New Jersey, USA zinc deposits. Like many of the famous Franklin fluorescent minerals, it is nondescript white in daylight and is not known in well formed crystals.See Franklin Furnace for a discussion of these deposits. Hardystonite has a chemical composition of Ca2ZnSi2O7. It was frequently found with Willemite (fluoresces green) and Clinohedrite (fluoresces orange).
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General Information:
 Chemical Formula:
Ca2ZnSi2O7
 Composition:
(Molecular Weight = 313.71 gm)
Calcium 25.55 % Ca
Zinc 20.84 % Zn
Silicon 17.91 % Si
Oxygen 35.70 % O 
 Empirical Formula:
Ca2ZnSi2O7
 Environment:
Metamorposed zinc deposits.
 Locality:
Franklin, Sussex Co., New Jersey, USA.
Physical Properties:
 Cleavage:
[100] Perfect, [110] Fair
 Color:
white, light brown, or pink.
 Density:
3.4
 Diaphaniety:
Transparent to translucent
 Habits:
Massive - Granular - Common texture observed in granite and other igneous rock., ,
 Hardness:
3-4 - Calcite-Fluorite
 Luminescence:
Non-fluorescent.
 Luster:
Vitreous (Glassy)
 Streak:
white
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