These acanthite crystals are from the Chispas Mine, Arizpe, Arizpe Municipality, Sonora, Mexico. This was a silver mine located on the Chispas vein that operated from the 1880’s until 1907. It contained 15 different minerals and is well known for the acanthite crystals that were found there. This piece is an attractive matrix free cluster of well defined acanthite crystals. They have elongated habits with hoppered or skeletal characteristics. They have a steely gray color and sub-metallic luster. They measure 1 1/4 x 7/8 x 1/2 inches or 32 x 22 x 12 mm.