Geology, Aurora Phosphate Mine, NC Coastal Plain,NC Minerals
North Carolina is one of the more notable states in this country for its variety of gems and gem minerals that have been found and mined within its borders.
Joseph Hyde Pratt, 1932; North Carolina State Geologist 1906-1924
Amethyst, aquamarine, emerald, hiddenite, ruby, and sapphire are among a few of the gems that lure collectors from around the world to visit North Carolina.
While some discoveries are due to industrial mining activities, many are the result of hobbyist gem and specimen mining. From the mid to late 1800s to the early 1900s, the mining of gemstones was a minor yet entertaining industry. During the late twentieth century, numerous mines opened to recreational collecting, thus supporting the local economies of the west-central region of North Carolina. Below are descriptions of a few gem varieties.
Amethyst: 
A purple/violet variety of quartz, a tectosilicate belonging to the SiO2 Group. Its purple color is due to the presence of trace amounts of iron as [FeO4]4- color centers. Amethyst is found in Stokes, Burke, Lincoln, Iredell, Macon, Moore, Warren, and Franklin counties.
Aquamarine: 
A blue to blue-green variety of Beryl (beryllium aluminum silicate: Be3Al2(Si6O18)) whose North Carolina type is well respected in the gem industry. Aquamarine is mainly associated with granitic pegmatites in Alexander, Avery, Cleveland, Haywood, Jackson, Macon, Mitchell, Rutherford, Transylvania, and Yancey counties.
Emerald: 
Adopted in 1973 as the State Gem of North Carolina, the emerald is a green gem variety of beryl (beryllium aluminum silicate: Be3Al2(Si6O18)). It was first discovered by farmers in Alexander County during the mid-1800s and later in Mitchell County in 1894-95. The "green bolts" were not identified until renowned mineralogist W.F Hidden visited the area (around 1871) to seek platinum for Thomas Edison. 
North Carolina is currently the only source of gem quality emeralds in the United States. Below is a list of a few notable emerald discoveries from North Carolina.
1880s: an 8.5 inch emerald was discovered
1969: the Rist Mine yielded a 1,438 carat emerald, the largest crystal ever discovered from North America
1969: the 13.14 carat "Carolina Emerald" was acquired by Tiffany & Company, New York
2009: The "Carolina Emperor", a 310 carat emerald was discovered in Alexander County. It was later cut to 64.83 carats and is referred to as the largest cut emerald ever found in North America.
2012: A pocket of emeralds were discovered in Alexander County totaling over 480 carats.
Hiddenite: 
Grass-green gemstone is unique to Hiddenite, Alexander County, North Carolina where it was discovered by (and named after) mineralogist W.E. Hidden in 1880. The nearby town was also renamed Hiddenite in honor of this exceptional mineral. It is a rare chrome-bearing form of spodumene, a lithium-rich aluminum silocate (LiAlSi2O6). It was discovered by and subsequently named for mineralogist W.E. Hidden. A nearby village was also renamed Hiddenite to honor this unique mineral.
Rhodolite: A pink variety of garnet unique in North America to North Carolina. Pale pink, to rose-red, to purple, rhodolite was discovered in 1893 in Asheville and later discovered while for ruby in the Cowee Valley in 1895. A mixture of two parts pyrope (Mg3Al2Si3O12) garnet and one part almandine (Fe3Al2Si3O12) garnet, it is named for its color resemblance to the blooms of rhododendron.
Ruby:
Is the blood red variety of corundum (Al2O3) of the Hematite group. Since the mid-1800s, gem varieties of ruby have been documented in Macon County near Franklin. In 1871 an attempt to mine this material was made at Corundum Hill near Cullasaja. Many fine gem varieties if ruby have also been found in the Cowee Valley gravels (and adjacent localities) near Franklin, NC. The rubies from this area of North Carolina approach the finest Burmese quality stones.
Sapphire: Encompasses the all color varieties of corundum except blood red (reserved for the ruby). The first regular mining of sapphire occurred in 1871 in Macon County at the Corundum Hill Mine. Later mining activities in 1892 in Jackson County yielded 400 tons of sapphire with 25 of that tonnage being pure crystals). In 1888 a notable sapphire, a 1.025 carat "blue star" sapphire, was discovered near Canton.
Be sure to take a tour of our collection of rocks and minerals on display in our Learning Center. Also check out our new
Fluorescent Mineral Room! It is sure to spark the wonder in all who enter!
References:
Klein, Cornelis, and Cornelius S. Hurlbut, Jr. Manual of Mineralogy (after James D. Dana), 21st Edition. New York: Wiley & Sons, 1977. Print.
Seaman, Jean H. "Mining." Encyclopedia of North Carolina. Ed. William S Powell. Chapel Hill: University Of North Carolina Press, 2006. 748-751. Print.
Ralph, Jolyon. Mindat.org. N.p., Spring 2014. Web. April & May 2014.
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Reed, Jeff. Mineral Resources. NCDENR Division of Energy, Mineral and Land Resources, North Carolina Geological Survey, n.d. Web. April & May 2014.
