Oil shale. Colorado 70 billion barrel oil yield in state shale. Post Ap 6, 1949 p.1 RMN Ap 7, 1949 p.11 Reserves held worth $750 billion. Post Mr 15, 1951 p.68 Where does the state rank in oil shale reserves? First. RMN My 5, 1951 p.5,6 Great reserves in Colorado; obstacles for tapping them. Cervi's Journal S 24, 1955 p.91 Rocky Mountain oil shale backed by government for new experiments. Post Jy 19, 1957 p.36 Union shale mine near Grand Valley goes underground. Post F 5,.1958 p.21