ELK CREEK, Neb. (AP) – Exploratory drilling in southeast Nebraska shows that other rare elements are lurking near a deposit of a valuable and rare heat-resistant element called niobium.  Canadian firm Quantum Rare Earth Developments released the latest test results Tuesday. This summer’s test results will help determine whether Quantum will build a mine near Elk Creek to retrieve niobium and these other rare elements from more than 500 feet underground. The U.S. currently imports nearly all the niobium that’s used in this country to harden steel and make it more heat-resistant for industrial uses. Some of the other rare earth elements that have been found at the site are used in cell phones, wind turbines, hybrid car batteries and other applications.