His membership in the Mormon Church led him to serve a mission in 1888 to 1891 in the Southern States Mission. His dreams continued and he was known as a missionary with prophetic abilities. Following his missionary service, Koyle returned home to his wife and family to resume farming.
In August 1894 he experienced a dream in which he was visited by a figure from another world. The visitor carried him to a high mountain east of Koyle's house and into the mountain, showing him the various strata and explaining the meaning of the minerals. The visitor showed Koyle an ancient "Nephite" mine with large rooms of mined-out ore bodies. The rooms contained treasure and artifacts of an extinct civilization. Koyle was instructed that he was to open a mine and extract gold for the welfare of "his" people. Specific instructions were given for the mine development leading to rich ore bodies. The riches would be found and released to him and his followers during a time of world crisis. The wealth would be spread to others through Koyle and the people organized around the mine. In this way the name "Relief Mine" was attached to the project. The heavenly messenger made it known that the wealth would not be available for "self gratification." The dream was repeated for a total of three times. Koyle talked of his dream to friends and others for support. In 1909 the Koyle Mining Company was formed with 114,000 shares of stock issued at $1.00 per share.
Koyle's dreams continued. He predicted the First World War and the economic crash of October, 1929. He foresaw "horseless carriages" bigger than railroad cars going down the road at great speeds. He especially received instruction on how to develop the mine. Plans included air shafts, escape ways and drainage tunnels. Instructions came to build a processing mill and storage bins for grain. By 1910, Koyle was appointed bishop of the Leland Ward in Spanish fork. The mining activities closely coupled with his church work attracted attention from the Mormon Church leaders. Apostle James E. Talmage, a geologist by training, came to look at the Dream Mine claims and could find no evidence that precious metals would ever be found in the strata being explored. The Mormon Church spoke out against the Koyle mine and associated activities and released John H. Koyle from the bishopric. However, Koyle's ongoing success as a seer and visionary continued to attract supporters and money, including some members of the Mormon Church leadership. Koyle was getting a mixed message from the Church. For a time, Koyle moved some members of his family to Idaho to pursue farming and while there Koyle was appointed to another bishopric as a councilor, but released when the Mormon leadership learned of the appointment. He continued to attract opposition from the Church for the rest of his life. He negotiated a repudiation of his claims, in 1947 and then reversed himself almost immediately and was excommunicated from the Church 18 April 1948. John H. Koyle died 17 May 1949 in Payson.
The mine continued in fits and starts under the leadership of Quayle Dixon for another twenty-three years. In 1961, a new company, The Relief Mine Company, succeeded the Koyle Mining Company and continued to do the minimum $100 per claim annual assessment work. Little more can be said about the often promised Koyle Dream Mine.