Sapphires
During the gold rush a prospector named Jake Hoover was not doing so well at gold panning had collected a box of "little blue stones" and sent them for analysis. The little blue stones turned out to be some of the world's finest sapphires. The gems are called Yogo sapphires after the canyon in which they are found near Lewiston, these sapphires are famous for their flawless clarity and cornflower blue color. Sapphires can be found in other areas of Western Montana, but they generally are not of the same quality of clarity and color. For those interested in hunting sapphires, however, there are some very nice stones that can be found in the state.
Amethyst and Quartz Crystals
Crystal Park is a 220-acre area of the Pioneer Mountains about 70 miles from Butte that is a designated rock-hunting site. Beautiful crystals and scepters of amethyst, quartz and smoky quartz crystals are the prize at this site. It is a well-trafficked area, but before the site was turned into an official rock-hunting site there were attempts to mine the area. One shaft was dug 150 feet deep and the workers were still digging up fine crystals. Quartz and amethyst crystals also can be found in the Lolo pass area near the Idaho border. Many of the amethysts and quartz crystals found in Montana are of gem quality.
Garnets
Garnets are found in concentrations in several areas of Montana. In Madison County, the Ruby River contains deposits of pyrope-almandine crystals that range from bright reds to pink or orange-tinted reds. There is also a heavy deposit where Alder Gulch intersects the Ruby River Valley. The Greenhorn and Tobacco Root mountain ranges are the source of these gems and many locations exist where you can hunt the gems in that region. These gemstones also are associated with the sapphires of the state, so those hunting for sapphires have the bonus of pocketing a few of these gems during their hunt.
Other Crystals
Calcite crystals are found in several areas of Montana. Some of the caves at the top of the Pryor mountains at the Wyoming border are lined with these beautiful crystals. The Drummond area also produces calcite crystals. Yellow barite crystals are found in the Indian Head Rock area just west of Basin. Those looking for topaz may find crystals on Strawberry Butte in the Helena area. There are 437 validated minerals on the Mindat directory of Montana minerals. The only real trick to finding wonderful crystals in Montana is to get out there and look for them.