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 piece consists of a limonite or goethite matrix that hosts vugs and exposed veins of glistening mimetite crystals. The crystals range in color from greenish-yellow to yellow and they have a rod to barrel shape. This piece measures 3 x 2 1/4 x 2 1/8 inches or 76 x 57 x 53 mm.