For the railfans: The Rio Grande Zephyr, train No 17 passes the west switch Radium (siding) during its 14 hour journey from Denver, Colorado to Salt Lake City, Utah. For the geography fans: Radium is a small rural unincorporated community in southwestern Grand County, Colorado, United States. The community sits in the mountains along an isolated stretch of Colorado River downstream from Gore Canyon and southwest of Kremmling. For the science fans: Radium is a chemical element with symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals.