Celestine-bearing geodes from Wayne and Emery counties, southeastern Utah: Genesis and mineralogy

Geodes containing celestine with associated quartz, calcite, chlorite, and other minerals occur in the Jurassic Curtis Formation of Emery and Wayne counties off the east and south flanks of the San Rafael Swell in southeastern Utah. The two areas discussed in this article produce geodes to 25 cm wide containing bladed to tabular celestine crystals that are as much as 4.5 cm in length. An evaporative littoral system resulting in the formation of anhydrite nodules is proposed as the initial environment for this deposit. Subsequent silicification of the nodules and, in some cases, the formation of hollow spaces within the silicified nodules, provided a geode structure for the eventual crystallization of celestine and associated minerals.