Pyromorphite, Pb5(PO4)3Cl (Lead Chlorophosphate), is analogous to Mimetite with the Phosphate (PO4) 3- ion replacing the Arsenate cation. Although the properties of the two minerals are almost the same because of this, colour can usually be used to distinguish between the two, Mimetite being yellow and Pyromorphite being yellow-green. It is a secondary mineral ocassionally used as an ore of lead. 

Description: A large pale brown crystalline matrix on which sits an extensive layer of extremely well formed Pyromorphite crystals. Most crystals are sharp, well-terminated and undamaged. The colour is dark green. Bright luster which shows up particulalry well under good illumination.

Location: Balliway Rigg, Caldbeck Fells, Cumbria, England.