Non-Acid Generating rock (NAG) is rock that in surface weathering/oxidizing conditions produces no acid. Our current test results show that most of the excess rock resulting from mining at Black Butte is non-acid generating. This is good news as this rock contains sufficient carbonate minerals to neutralize any potential acid generation from mineralized material. However, Tintina is placing all NAG rock from mining with the PAG (Potentially acid generating) rock into its cemented tailing facility where they will be secured with the tailings inside a sealed 100-mil liner and buried. No NAG or PAG rock will be left outside the CTF facility.