These pyrargyite crystals are from Guanajuato, Mun. de Guanajuato, Guanajuato, Mexico. This is a gold and silver mine that contains 16 different minerals including pyrargyrite. It is a silver sulfide containing the elements Ag, Sb and S. This is a cluster formation of about a dozen well defined crystals of pyrargyrite. They have a silver-black color and a reddish hue which is why they are often referred to as “Ruby Silver”. This is a thumbnail sized piece and it measures 15/16 x 1/2 x 5/16 inches or 24 x 12 x 7 mm.