What is "matlockite"

n. (context mineralogy English) A tetragonal-ditetragonal dipyramidal mineral containing chlorine, fluorine, and lead.

Matlockite is a rare lead halide mineral, named after the town of Matlock in Derbyshire, England, where it was first discovered in a nearby mine. Matlockite (chemical formula: PbFCl) gives its name to the matlockite group which consists of rare minerals of a similar structure.