Selenite crystals and siderite with pyrite pseudomorph baseLocale: Potos Mine, Santa Eulalia, Chihuahua, Mexico Approx dimensions: 4 x 3 x 2. 5" Approx weight: 490g (1 lb) This specimen is a sampler mix of minerals from the Potos Mine, with selenite and light to orange yellow siderite on a heavy base composed of several minerals. Selenite is the crystal clear form of gypsum, though the two terms are often used interchangeably. Selenite is one of the more common minerals to come from Mexico, which is known for