These mimetite crystals are from the Ojuela Mine in Mapimi, Durango, Mexico. There a over 115 different types of minerals in the mine including mimetite. It is an arsenate that contains the elements Pb, As, O and Cl. This specimen consists of a plate of complex formations or clusters of mimetite crystals. They have a sugar-like luster and change color when viewed from different sides as shown in photos 2 & 3. This piece measures 2 3/8 x 2 x 1 1/4 inches or 60 x 50 x 32 mm.