Mineral Species: Mimetite

Chemical Formula: Pb5(AsO4)3Cl

Chemical Name: Lead Chloroarsenate

Mineral Class: Arsenate

Mineral Notes: Mimetite is analogous to Pyromorphite with the arsenate (AsO4) 3-, replacing the phosphate cation (PO4) 3-. Although most properties are almost the same because of this, colour can usually be used to differentiate between the two, Mimetite being yellow and Pyromorphite being green.

Description: A brown matrix on which sits an 'enormous' crystal of Mimetite. The crystal measures almost 1cm across and has a very unusual round garnet-like form. The colour is a very gentle pastel yellow, enhanced by a waxy luster. A very aesthetic display specimen.