This fluorite is from Melchor Muzquiz in the Mun. de Melchor, Coahuila, Mexico. Fluorite is a gangue mineral found in association with the lead and silver mines of the area. Fluorite is in the Halide Group of minerals and it contains the elements Ca and f. These crystals are colorless with purple phantoms just below the surface. They have a nice translucence when back lighted as in photo 2. Their luster varies from greasy to vitreous.The crystals have a modified cubic morphology with stair-step edges and prism faces. This piece is a floater with terminated, recrystallized, surfaces on the former attachment points (photo 3). This specimen measures 3 1/4 x 2 7/8 x 2 inches or 8.2 x 7.4 x 5.0 cm.