Lime and Gypsum
Outcrops of the Cretaceous Greenhorn and Niobrara Limestones provide most of the cement materials in Colorado. A number of plants along the mountain front, including a completely automated and dust-free one near Lyons, provide the major population centers with millions of tons of cement each year.
Colorado is richly endowed with gypsum, useful in cement and plaster manufacture and for ornamental stone and sculpture. Along the eastern front of the mountains, gypsum occurs in the Triassic Lykins Formation; in the Mountain Province, it is abundant in Pennsylvanian [sedimentary rocks]. Particularly high-quality Pennsylvanian gypsum is quarried at the town of Gypsum, west of Eagle.
The Colorado portion of the Paradox Basin, in the [Plateau] Province, contains immense deposits of Pennsylvanian gypsum. Here, rocks near the surface have been pushed up into sharp northwest-trending faulted [anticlines] by upward movements of gypsum and salt from depths of several thousands of feet. The soluble salt and gypsum cores of these structures have been washed away more rapidly than the surrounding layers of sandstone and shale, leaving depressions such as Gypsum Valley, Paradox Valley, and Sinbad Valley, on the crests of the anticlines. Red and yellow Triassic sandstones and shales, especially the Chinle Formation and the Wingate Sandstone, [dip] away from these valleys. Exploratory wells indicate that vast masses of salt and gypsum are present beneath the surface, and may extend to depths greater than 10,000 feet.