Uranium ore support a neutron-mediated chain reaction). Uranium, thorium, and potassium are the main elements contributing to natural terrestrial radioactivity. Uranium has the highest atomic weight of the naturally occurring elements and is approximately 70% denser than lead, but not as dense as tungsten, gold, platinum, iridium, or osmium. It is always found combined with other elements. Along with all elements having atomic weights higher than that of iron, it is only naturally formed in supernova explosions. The primary uranium ore mineral is uraninite (UO) (previously known as pitchblende). A range of other uranium minerals can be found in various deposits. These
Galena, Illinois top-ten "Charming Small Towns". Galena is located at (42.418171, −90.431472) along the Galena River, which is one of many tributaries of the Mississippi River. According to the 2010 census, Galena has a total area of , of which (or 99.83%) is land and (or 0.17%) is water. Galena is located in the Driftless Zone, an area that was not covered by glaciers during the recent ice ages. This area, which includes the far northwestern corner of Illinois, escaped glaciation, while almost the entire state was glaciated, nearly to its southern tip. Because it escaped glaciation, this area is known for