On the western flank of the Mineral Mountains, between Beaver and Milford, is the Rock Corral Recreation Area. This site is purported to have good specimens of smoky quartz and feldspar. I originally set out to explore this as well as the Porcupine Ridge beryl site on the eastern side of the range, but ended up not having the time to do both.
It may be of note to some readers that there is no overnight camping allowed in the Rock Corral site itself, and space for larger campers and RV’s is limited throughout the area. I ended up camping a few miles to the north along Ranch Canyon Road.
I started off in the morning at the Rock Corral site, exploring the large granite formations for vugs and productive seams. The area is actually quite brushy and a lot of the granite is difficult to access without some serious bushwacking. The ground is more or less littered with milky and cloudy gray quartz and microcline, but nice vitreous, well-terminated specimens are scarce. I managed to find a few small specimens laying in the float and a couple of exposed vugs that hadn’t been thoroughly worked.
Later in the day, I left to explore down lower in Rock Corral canyon and along Ranch Canyon. For the most part, all of the granite in the area is similar and yielded the same type of material. 
At one time the region was frequented by Native Americans, so if you do visit, keep an eye out for artifacts as well. I hiked through a clearing strewn with obsidian flakes and partially worked points. Overall the area is very appealing, with running water at the bottom of the steep arroyo even in mid-September of a dry year. I would recommend an aside if you are ever in these parts, even for just the great desert scenery.