The creeks and valleys around the town of Franklin are reputed to contain the largest variety of minerals in the world. Though there are not enough large or contiguous deposits to make industrial mining profitable, minerals and gemstones occur in sufficient quantities to support a large tourism trade for amateur gem hunters.
Among the minerals and gemstones found in the Macon County area are kyanite, sillimanite, granular mica, quartz varieties, rutile, corundum, and magnesium-aluminum garnet. The gems most often associated with the Franklin area, however, are rubies and sapphires, which are the red and blue gem varieties (respectively) of corundum, an extremely hard aluminum-oxide mineral. The various colors found in ruby and sapphire gemstones are caused by the presence of trace amounts of elements such as chromium, iron, and titanium, among others.
Cowee Valley's unique geology has endowed the area with equally unique rubies and garnet gems. While rubies of various reddish tints have been found at mines in other parts of the world, none has produced the deep red ruby variety found in the Caler Fork area of Cowee Valley. These rubies are of extremely high quality.
The same holds true for the garnets that occur here. Rhodolite garnets are found in Macon County, but are very unusual and highly sought after. The name rhodolite is derived from the Greek rhodon, for rose (which also gave rise to the name for the rhododendron flower), and rhodolite garnets exhibit a very light to very dark rose color. As with Franklin-area rubies, rhodolite gemstones occur elsewhere, but the best specimens known to date are found only in the Cowee Valley area.