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
Ore Mountains mining in the southern forelands of the Ore Mountains. Europe's largest deposits of lithium-bearing mica zinnwaldite in Cínovec, a Czech village between town of Dubí and the border with Germany which gave its old German name Zinnwald to the mineral, are expected to be mined starting 2019 (as of June 2017). When several Ore Mountain passes were upgraded into "chaussees" in the 19th century, and the Upper Ore Mountains were accessed by the railway, tourism began to develop. One of the early promoters of tourism in the Ore Mountains was Otto Delitsch. In 1907, a memorial was erected to him