Autunite Autunite Author: Tim This small sample is a hunk of Autunite, which chemically is hydrated calcium uranyl phosphate, from the Daybreak Mine. Autunite in its small display case. Up close up you can see the layered structure. It is noticeably radioactive. A microscope view reveals the beautiful crystalline structure that is separating. A microscope view reveals the beautiful crystalline structure that is separating. A huge host of lines appear in the gamma spectrum.