Sclarite
Sclarite is an IMA-recognized mineral species in the carbonate class, with the chemical formula Zn₇(CO₃)₂(OH)₁₀.
It crystallizes in the monoclinic crystal system (space group A2/a).
Key properties: Mohs hardness 3–4; specific gravity 3.51; White streak; Vitreous luster; optically biaxial.
IMA symbol Sl, IMA status: approved, named in 1988.
Very rare on a museum specimen, in a veinlet possibly of hydrothermal origin, from a metamorphosed stratiform zinc orebody.
It is found associated with Gageite, leucophoenicite, chlorophoenicite, rhodochrosite, willemite, zincite, franklinite.
The mineral was named to honor Professor Charles Bertram Sclar (1925–2001), Geology Department, Lehigh University, Bethlehem, Pennsylvania, USA, who long studied the genesis of the Franklin deposit.