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, Alaska upon the closure of Galena Air Force Station. As Galena is incorporated as a first-class city and located in the Unorganized Borough, it is required by state law to operate its own schools, Galena City School District, apart from the Rural Education Attendance Areas which otherwise prevail outside of incorporated boroughs. Along with other such cities across Alaska, Galena's school district operates a boarding school and a correspondence study program, to increase state funding which would not otherwise be available with the local pupil base. Galena has three schools. Galena City School is primarily for local K–12 students. There is