The Mineral Mountains, located in Beaver County, make up the largest exposed plutonic body in Utah. Rock compositions range from quartz monzonite in the northern half of the pluton to granite around Rock Corral Canyon in the south.
Excellent crystals of smoky quartz and feldspar are found in vugs or cavities in the granite. They formed when cooling fractures in the granite were filled by late-stage pegmatites consisting of quartz, microcline, and plagioclase. Quartz occurs as clear to smoky, euhedral crystals up to three inches long while microcline is commonly found as euhedral, equidimensional crystals averaging approximately 0.75 inches in width. Occasionally, large pseudomorphs of limonite after pyrite can be found in these areas as well.
Directions:
From the town of Milford, travel 0.7 miles south of the railroad tracks on State Route 21 where a Corral Recreation Area sign will instruct you to turn left (east) from the highway. This road is paved for a short distance but then turns to sand. Continue from the turn-off 5.4 miles to an intersection. Take the left fork and continue for 1.2 miles to another intersection. Keep right at this intersection for 2.7 miles to the first outcrop or inselberg on the left. You can park here or continue to the picnic area in Rock Corral Canyon.
