Hardystonite , Clinohedrite , Calcite , Willemite Locality: Franklin Mine , Franklin , Franklin Mining District, Sussex County, New Jersey , USA ( Locality at mindat.org ) Size: 7.0 x 6.0 x 3.2 cm. A CLASSIC, multi-fluorescent specimen with 4 minerals from the famous Franklin Mine containing: BLUE hardystonite (ultra-rare Type Locality); ORANGE clinohedrite (ultra-rare Type Locality); RED calcite; and GREEN willemite from the Parker Shaft. This specimen is particularly rich in hardystonite. Ex George Elling Collection, a noted Franklin/Sterling Hill collector. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Clinohedrite
A rare hydrated calcium-zinc silicate occurring as monoclinic veinlets and fracture coatings.
Intro adapted from Wikipedia (CC BY-SA).
Clinohedrite is an IMA-recognized mineral species in the silicate class, with the chemical formula CaZn(SiO₄)·H₂O.
It crystallizes in the monoclinic crystal system (space group Cc).
Key properties: Mohs hardness 5.5; specific gravity 3.28–3.33; Brilliant, glassy; pearly on {010} luster; refractive index 1.666; optically biaxial.
IMA symbol Cnh, grandfathered status — known before the IMA’s founding, named in 1898.
Found in a metamorphosed stratiform zinc orebody (Franklin, New Jersey, USA).
It is found associated with Hancockite, nasonite, glaucochroite, roeblingite, calcite, willemite, axinite, larsenite, hodgkinsonite, franklinite (Franklin, New Jersey, USA); stringhamite.
Its name comes from the Greek klino, for incline, and hedra, for face, for the inclined facial character of the crystal morphology.