Outstanding yellow crystals of laphamite associated to white crystal aggregates of the also very rare K silicofluoride mineral hieratite. From: Shamokin, Northumberland County, Pennsylvania, United States of America. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Laphamite
Laphamite is an IMA-recognized mineral species in the sulfide class, with the chemical formula As₂Se₃.
It crystallizes in the monoclinic crystal system (space group P2_1/n). It is a member of the Orpiment structural group.
Key properties: specific gravity 4.5; Reddish orange streak; Resinous luster.
IMA symbol Lpm, IMA status: approved, named in 1985.
Found as a secondary incrustation, probably by sublimation, on clinker adjacent to a surface vent on a burning pile of waste material from an anthracite coal mine.
It is found associated with Arsenolite, orpiment.
The mineral was named to honor Dr. Davis M. Lapham (1931–1974), former Chief Mineralogist of the Pennsylvania Geological Survey.