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 city was $24,117. About 5.9% of families and 7.9% of the population were below the poverty line, including 13.8% of those under age 18 and 7.0% of those age 65 or over. Galena is a popular tourist destination hosting well over one million visitors each year. Galena is also popular with Chicagoans, many of whom keep second homes in the area. 85 percent of the structures in Galena are within the Galena Historic District, which is listed on the National Register of Historic Places and greatly contributes to the city's popularity. The Old Market House State Historic Site, built in