A sparkling cluster of floating silvery balls, like liquid metal, this is a 2.5 x 2.4 x 1.5 cm group of silvery spheres of this rare species, franckeite. Minor zinkenite is also present. From Luis Miguel Fernandez Burillo (Zaragoza, Spain) on February 1, 2015, in Tucson, Arizona. Photo by Jeff Scovil. An exceptional rarity with a shape, a style, a color that all contribute something totally different to any significant thumbnail collection.