This acanthite is from the Sirena Mine in Guanajuato, Mexico. This is a silver mine on the same vein as the San Juan de Rayes Mine. It contains 9 different minerals including the silver sulfide acanthite. This piece consists of a quartz matrix that hosts deposits of crystalline and crystal acanthite. It measures 2 7/8 x 1 5/8 x 1 inches or 73 x 41 x 25 mm.