Iconic controls 808 placer claims totaling 25.25 square miles (65.4 km2) over a major gravity low. The enclosed Smith Creek Valley Basin covers 582 square miles (1,507 km2), which is slightly larger than Clayton Valley Basin where lithium brines are produced. Smith Creek Valley is over +40 miles (+64 km) long in a north-northeast direction and averages 9 miles (14.5 km) in width. The vast majority of rock weathering into the basin is felsic ash flow tuff, which is an excellent source of lithium. The Smith Creek basin itself is composed of alluvium surrounding a mud flat, a remnant of a paleo-lake. Brine evaporate is found around the edges of the mud flat, but not in sufficient quantity to be mapped as a unit. The basin is bounded by a series of step faults that down-dropped the central basin several thousand feet. Some of these step faults serve as fluid conduits for present day hot springs that border the mud flats. Activity in this geothermal location is believed to be a major contributing factor to the presence of economic lithium brines. Previous shallow drilling by the USGS in the valley for a ground water study discovered the presence of brine, though it was not assayed for lithium. A gravity study of the Smith Creek Valley area completed by Frank Fritz of Fritz Geophysics of Fort Collins, Colorado, discovered a large gravity low under the southern portion of the valley. The mud flat sediments have a calculated thickness of over 4,000 feet (1,220 m). Sampling of brine evaporates deposited in the mud flat downslope of hot springs, located just northwest of the flat, returned lithium values of up to 470 ppm. It is possible that the lithium is being brought to the surface from brine at depth by geothermally heated groundwater.