Feldspar

 

 

Introduction

 

Feldspar is the most common rock-forming mineral (about 60% of the earth’s crust) (Kauffman and Van Dyk, 1994). The mineral name feldspar is derived from the German words feld + spar. The word "feld" is "field" in German and "spar" is a term for light colored minerals that break with a smooth surface. Feldspar minerals are usually white or very light in color, have a hardness of 6 on the Mohs’ Scale of Hardness and perfect to good cleavage (plane of breakage) in two directions.

Feldspar is a common name that applies to a group of minerals with a general chemical formula of x Al(Al,Si)3O8, where x can be sodium (Na) and/or calcium (Ca) and/or potassium (K). (Specific compositional varieties (i.e. albite, microcline…) are discussed under Mineral Descriptions).

Feldspar occurs in igneous, metamorphic and sedimentary rocks and thus can be found throughout North Carolina. It is more commonly found in igneous and metamorphic rocks of the Blue Ridge and Piedmont provinces. Feldspar weathers to kaolin which is the main clay mineral used in ceramics and fine pottery.

 

History and production

 

The history of feldspar production is directly tied to the history of mica production and past mining of kaolin in the Blue Ridge since they are associated minerals. In accounts from 1875 and 1876, geologists reported finding evidence of old mica mining. They noted numerous prospect pits dotting the hillsides, some of which were very extensive in size with trees three feet or more in diameter rooted on large spoil mounds next to the pits. Native Americans could have worked these mines for mica for ornaments and/or for kaolin, a weathering product of feldspar. Early known production extends back to the 18th century when it was said the Cherokee Indians mined and sold partially kaolinized feldspar prior to 1744 (Watts, 1913; Stuckey, 1965), presumably for shipment to England for ceramic use.

Feldspar was first mined along with kaolin (weathered feldspar) in an area near Sylva in Jackson County in the late 1800’s. First recorded modern mining in the Spruce Pine Mining District of Avery, Mitchell and Yancey counties was in 1868 when feldspar ore was shipped from the Deer Park mine. The raw material had to be shipped to grinding mills located in Ohio and New Jersey. In 1914, a grinding mill was built in Erwin, Tennessee, which led to the opening of more mines. Since 1917, North Carolina has been the leading producer of feldspar in the United States.

The initial production of feldspar was from pegmatite bodies. Pegmatites are bodies of rock commonly of granitic composition that consist mainly of unusually large crystals or masses of quartz, feldspar, and mica. Pegmatites crystallize during the last stages of injection of granitic magma. The magmatic fluids are rich in water and cool so slowly that the crystals grow larger than usual. The grain size can range from less than an inch to more than a foot but rarely greater than three feet. Pegmatites range in size from small lens, one to a few feet in thickness, to large tabular bodies tens of feet thick and hundreds of feet long.

Past production came from the larger pegmatites. Mining was labor intensive. Ore was hand cobbed (hand-size pieces are broken by hammer) and sorted by hand.

In 1946, the US Bureau of Mines (USBM) developed a new mineral dressing technique to process mica and feldspar ore by froth flotation (floating a specific mineral on foam to separate it from other minerals). In addition to the USBM work, North Carolina State University’s Minerals Research Laboratory at Asheville and the feldspar industry continued to refine the technique on the ore of the district. This breakthrough turned attention away from the pegmatites and focused exploration and mining on the much larger, more uniform alaskite bodies.

The Spruce Pine alaskite is a light colored, medium- to coarse-grained feldspar-quartz-muscovite rock. Alaskite bodies can occur in masses up to several miles in diameter. The average mineral composition of the alaskites is oligoclase feldspar (40%), quartz (25%), microcline feldspar (20%), and muscovite mica (15%). Alaskite also contains minor accessory minerals such as biotite, garnet, epidote, apatite and pyrite (Lesure, 1968; Wiener and Merschat, 1977). In the Spruce Pine district, pegmatites are closely associated with the alaskite bodies and are thought to have crystallized from fluids derived from the alaskite masses in the final stages of crystallization of these igneous bodies.

North Carolina produced 54% of the total US feldspar (feldspar rock and feldspathic sand) production (Potter, 1996; Potter, 1997). Of the feldspar rock produced, North Carolina produced 96% (Alex Glover, 1999, pers. com.). Most feldspar in North Carolina is produced from alaskite bodies in the Spruce Pine Mining District in Mitchell County. The district is about 250 square miles in area – 10 miles wide and 25 miles long.

Feldspar is currently produced as a by-product of mining mica from pegmatites and other rocks associated with the Cherryville quartz monzonite rock (a type of granitic rock) in Cleveland County. Until recently, feldspar was also recovered from the Kings Mountain district in Cleveland and Gaston counties as a by-product of mining spodumene (source of lithium) from pegmatites.

 

Map of Feldspar Resources - North Carolina

Map of Feldspar Occurrences - Spruce Pine District

 

Potential resources. The production of feldspar in North Carolina comes from the Spruce Pine District. In order to separate feldspar from quartz, hydrofluoric acid is used. Some fluoride is discharged into the North Toe River. Existing operations cannot increase production because government regulations have put a limit on the amount of fluoride in stream water. In order to expand, the feldspar industry must look outside the Spruce Pine District for new feldspar resources (Carpenter, Schlanz and Carpenter, 1995).

Feldspar occurs in numerous granitic rocks, located particularly in the central portion of the state. In the late sixties and early seventies, the NCSU Minerals Research Laboratory at Asheville and the Division of Mineral Resources undertook an evaluation of feldspar resources in the state. Of the 218 samples evaluated, 55 samples (25%) had potential for further tests as a feldspar resource (Neal and others, 1973).

In 1995, tests on several granitic plutons (igneous rock formed below the earth's surface) indicated that the Churchland pluton and the Rolesville granite in the Raleigh Belt contain high concentrations of potassium (K) feldspar (Carpenter, Schlanz and Carpenter, 1995). The Churchland pluton is located in central North Carolina in northern Rowan, Davie, Davidson, Guilford and Caswell counties, and the Rolesville granite is in Wake and Franklin counties.

 

Uses

 

Feldspar is used in the manufacture of glass products (70%), in ceramics and other products (30%) (Potter, 1996).

Feldspar is an important ingredient in the manufacture of glass. The raw material for glass consists of silica sand, soda ash (sodium carbonate) and limestone (calcium carbonate). Feldspar adds certain qualities to the process. Alumina provides hardness, workability, strength, and makes glass more resistant to chemicals. NaO2 and K2O from feldspar are fluxes. Fluxes reduce the melting temperature so less energy is used and decrease the amount of soda ash needed (Kauffman and Van Dyk, 1994; Bourne, 1994). About 110 pounds of feldspar are used to produce one ton of container glass (soda bottles, e.g.), and 100 pounds are required to produce one ton of flat glass (Alex Glover, 1999, pers. com).

Thirty percent (30%) of feldspar production is used for manufacturing ceramics, especially in commodes and sinks. Italy produces twice the amount of feldspar than the US. In Italy, the majority of feldspar production is for ceramic tile. European houses have ceramic tile flooring as opposed to our usage of wall-to-wall carpeting. Should the use of ceramic tile flooring increase in the US, the demand for feldspar would greatly increase.

In the fabrication of ceramic material, feldspar serves as a flux to form a glassy phase at low temperatures, and as a source of alkalies and alumina in glazes. It improves the strength, toughness, and durability of the ceramic body and cements the crystalline phase of other ingredients. Feldspar is also used in paint, in mild abrasives, urethane, latex foam, and as a welding rod coating.

 

Mineral properties

 

Feldspar is the most common rock-forming mineral. Feldspar is a name for a group of minerals with a general chemical formula of x Al(Al,Si)3O8, where x can be one or more elements. Feldspar minerals are usually white or very light in color and have a hardness of 6 on the Mohs’ Scale of Hardness. Another physical property of the feldspar group is that the mineral has good cleavage in two directions. The cleavage breaks are about 86o for plagioclase feldspars (albite, oligoclase, andesine, labradorite and anorthite), at 90o for orthoclase and 89.5o for microcline. Upon weathering, feldspar minerals break down to form kaolinite, a clay mineral.

 

 

MINERAL DESCRIPTIONS AND SITES

 

Feldspar minerals can be subdivided into two groups - plagioclase feldspars, and potassium feldspars. Plagioclase feldspars are sodium / calcium aluminum silicates. The plagioclase feldspar series is:

 

Potassium feldspars are potassium aluminum silicates. The most common K (potassium) feldspars are microcline (amazonite, moonstone) and orthoclase.

 

  • The following mineral descriptions are taken from Cook (1978), Dana (1952) and Paris (1994).
  • In the Spruce Pine District of Mitchell, Avery and Yancey counties there are more than 700 mines listed that produced feldspar and/or mica in the past. There are probably two to three times as many prospects or borrow pits in the area (Lesure, 1968). Listed below, under the mineral descriptions, are a few collecting sites that are easy to get to in these counties.

     

    Map of Feldspar Mineral Occurrences

     

     

    Albite (moonstone)

    Chemical Composition: (Na,Ca)AlSi3O8

    Sodium, calcium (0 to 10%) aluminum silicate

     

    Class: Silicate

     

    Crystallography: Triclinic; pinacoidal

     

    Habit: Crystals commonly tabular. Usually massive, granular, lamellar. Twinning very common.

     

    Physical properties: Luster vitreous, sometimes pearly. Color white to colorless; occasionally bluish, gray, reddish, greenish depending on impurities. May have opalescent colors (moonstone). Streak white. Transparent to sub-transparent.

    Cleavage {001} perfect, {010} nearly perfect, {110} imperfect. Cleavage angle at 86o. Fracture uneven to conchoidal. Brittle. H. 6-6.5. S.G. 2.6-2.63.

     

    Occurrence: Albite is a very common mineral of the plagioclase group of feldspar.

     

    Mineral localities and descriptions of localities are from Wilson and McKenzie (1978) and Conley (1958). These locations have not been field checked for accuracy, minerals present or for accessibility. With the help of mineral collectors, it is hoped that the occurrences below can be verified and then classified as mineral collecting sites.

    Click for an explanation of "Headings in the Mineral Occurrence and Site Index" which are in the Mineral Occurrence Index.

    The site code (e.g., AVERY-002) refers to the site reference in the Mineral Occurrence Index.

     

    Avery County: The May-Meade (Maymeade) quarry (closed) along with epidote, chlorite, tremolite, calcite, thulite, azurite, malachite, and green quartz crystals (AVERY-003).

    Caswell County: Albite has been found in the pegmatite deposits south of Milton near Yarbro (CASWE-001).

    Cleveland County: High-quality moonstone has been found in several creeks in the west central portion of the county (CLEVE-001, CLEVE-002, CLEVE-003). Albite occurs at the Foote Mineral Company spodumene (lithium) mine (inactive) near Kings Mountain (CLEVE-013). This mine is closed to mineral collecting.

    Davie County: Fine-grained albite is associated with hornblende in an orbicular diorite rock in the south central portion of the county (DAVIE-003). The rock contains circular blebs of hornblende surrounded by fine white albite. It was once used as an ornamental stone.

    Mitchell County: Rare, doubly terminated albite crystals in a pegmatite dike are on private property, 1.5 miles northeast of Bakersville (MITCH-004).

     

    Mineral Collecting Sites

     

    Mitchell County: The Spruce Pine Mining District is the chief mica and feldspar producing area in the United States.

    Feldspar, plagioclase, quartz and mica (muscovite) occur at the McKinney mine (collecting fee charged) (MITCH-015). Other accessory minerals that occur are samarskite, garnet, autunite, torbernite, columbite, hyalite, amazonite, bornite, covellite, chalcopyrite, allanite, epidote, malachite, sphalerite and massive beryl.

    To get to the mine, take Highway 19-E west from Estatoe; at 1.3 miles turn left (south) on SR 1002; at approximately 4.8 miles turn onto SR 1100. The mine is on both sides of the road (now Emerald Village and the North Carolina Mining Museum).

    Feldspar, plagioclase, perthite, quartz and muscovite mica can be found at the Hootowl mine (abandoned) (MITCH-017). This mine can be reached by taking Highway 19-E west from Estatoe; at 0.37 mile turn left (south) on SR 1157; at 0.4 mile take the right fork; at approximately 0.9 mile mark the state road ends and a private road begins. The mine is on the left (east) side of the road. The Hootowl is shown and labeled on the Micaville 7 minute topographic map.

    Feldspar, plagioclase, quartz and muscovite mica, along with accessory minerals biotite, garnet and tourmaline (rare) are reported from the Sinkhole mine (abandoned) (MITCH-016). The mine can be reached by going 1.6 miles northwest SR 1191 from the intersection of SR 1191 and NC Highway 226; turn left on Highway 80; at 2.3 miles the mine is to the left just before SR 1182. This mine is shown on the Micaville 7 minute topographic map.

    Another collecting locale is at the Deer Park mine (abandoned) (MITCH-008) northwest of Spruce Pine. Feldspar, perthite, plagioclase, quartz and mica can be found with accessory minerals - thulite, hyalite and monazite. At the intersection of NC Highway 226 and SR 1162, north of Spruce Pine, turn left (southwest) onto SR 1162 (Penland Road). Travel approximately 1.6 miles to Penland and cross the bridge over the North Toe River. Turn immediately left (east) onto SR 1270 for a very short distance. After state-maintained road ends, continue on 4-wheel drive road that parallels the river to the mine area in bend of the North Toe River approximately 0.7th of a mile. This mine is shown on the Spruce Pine 7 topographic map.

     

     

    Oligoclase Plagioclase feldspar

     

    Chemical Composition: (Na,Ca)AlSi3O8

    Sodium, calcium (10 to 30%) aluminum silicate

     

    Class: Silicate

     

    Crystallography: Triclinic; pinacoidal

     

    Habit: Crystals commonly tabular, uncommon. Usually massive, cleavable, granular, or compact. Twinning common.

     

    Physical properties: Luster vitreous. Colorless, white, gray, greenish, yellowish, brown, reddish, depending on impurities; occasionally shows brilliant reflections from minute specks of hematite giving it a golden shimmer (sunstone). Streak white. Transparent to translucent. Cleavage {001} perfect, {010} nearly perfect, {110} imperfect. Cleavage angle at 86o. Fracture conchoidal to uneven. Brittle. H. 6-6.5. S.G. 2.63-2.67.

     

    Occurrence: Oligoclase occurs in the Spruce Pine District in western North Carolina and is a very common mineral in granites and gneisses.

     

    Mineral localities and descriptions of localities are from Wilson and McKenzie (1978) and Conley (1958). These locations have not been field checked for accuracy, minerals present or for accessibility. With the help of mineral collectors, it is hoped that the occurrences below can be verified and then classified as mineral collecting sites.

    The site code (e.g., AVERY-002) refers to the site reference in the Mineral Occurrence Index.

     

    Jackson County: Oligoclase occurs at the L.M. McCall feldspar and mica mine (abandoned) southeast of Pinhook Gap (JACKS-010).

    Mitchell County: Glass clear oligoclase occurs at the Hawk mine located 1.2 miles north of Hawk (MITCH-005).

    Yancey County: The Spruce Pine Pegmatite District crosses eastern Yancey County east of Burnsville. The Little Gibbs mine (abandoned) on the South Toe River, 1.5 miles northeast of Celo, contains glass clear oligoclase feldspar, which can be cut into faceted gemstones.

     

    Mineral Collecting Sites

     

    Mitchell County: The Spruce Pine Mining District is one of the chief mica and feldspar producing areas in the United States.

    Feldspar, plagioclase, quartz and mica (muscovite) occur at the McKinney mine (collecting fee charged) (MITCH-015). Other accessory minerals that occur are samarskite, garnet, autunite, torbernite, columbite, hyalite, amazonite, bornite, covellite, chalcopyrite, allanite, epidote, malachite, sphalerite and massive beryl.

    To get to the mine, take Highway 19-E west from Estatoe; at 1.3 miles turn left (south) on SR 1002; at approximately 4.8 miles turn onto SR 1100. The mine is on both sides of the road (now Emerald Village and the North Carolina Mining Museum).

    Feldspar, plagioclase, perthite, quartz and muscovite mica can be found at the Hootowl mine (abandoned) (MITCH-017). This mine can be reached by taking Highway 19-E west from Estatoe; at 0.37 mile turn left (south) on SR 1157; at 0.4 mile take the right fork; at approximately 0.9 mile mark the state road ends and a private road begins. The mine is on the left (east) side of the road. The Hootowl is shown and labeled on the Micaville 7 minute topographic map.

    Feldspar, plagioclase, quartz and muscovite mica, along with accessory minerals biotite, garnet and tourmaline (rare) are reported from the Sinkhole mine (abandoned) (MITCH-016). The mine can be reached by going 1.6 miles northwest SR 1191 from the intersection of SR 1191 and NC Highway 226; turn left on Highway 80; at 2.3 miles the mine is to the left just before SR 1182. This mine is shown on the Micaville 7 minute topographic map.

    Another collecting locale is at the Deer Park mine (abandoned) (MITCH-008) northwest of Spruce Pine. Feldspar, perthite, plagioclase, quartz and mica can be found with accessory minerals - thulite, hyalite and monazite. At the intersection of NC Highway 226 and SR 1162, north of Spruce Pine, turn left (southwest) onto SR 1162 (Penland Road). Travel approximately 1.6 miles to Penland and cross the bridge over the North Toe River. Turn immediately left (east) onto SR 1270 for a very short distance. After state-maintained road ends, continue on 4-wheel drive road that parallels the river to the mine area in bend of the North Toe River approximately 0.7th of a mile. This mine is shown on the Spruce Pine 7 topographic map.

    Yancey County: Feldspar (plagioclase), perthite, quartz and muscovite occur at the Ray (Wray) mica mine (abandoned) (YANCE-001). Other minerals reported are golden and aquamarine beryl, apatite crystals, clear oligoclase (plagioclase feldspar), biotite, amazonite, thulite, garnet, autunite, columbite-tantalite, tourmaline, zircon and rutile.

    To reach the mine, turn south onto NC Highway 197 from US Highway 19-E in Burnsville. Travel 0.9 mile to an intersection with SR 1109. Turn left (east) and travel along SR 1109 (Bowlens Creek Road) for approximately 1.4 miles to the intersection with SR 1192, nearly opposite the Bowlens Creek Church. Turn left (east) onto SR 1192 for about 0.3 mile where the state-maintained road ends and a 4-wheel drive road leads to mine workings a little further ahead on left. This site lies in the Pisgah National Forest.

     

     

    Anorthite

     

    Chemical Composition: CaAl2Si2O8

    Calcium aluminum silicate

     

    Class: Silicate

     

    Crystallography: Triclinic; pinacoidal

     

    Habit: Usually massive, cleavable, granular, or compact.

     

    Physical properties: Luster vitreous. Color white-gray, reddish. Transparent to translucent. Cleavage two perfect {010,001} at 86o. Fracture uneven to conchoidal (like the edge of a glass fragment). Brittle. H. 6. S.G. 2.74-2.76.

     

    Occurrence: Anorthite occurs in some ultramafic igneous rocks.

    Mineral localities and descriptions of localities are from Wilson and McKenzie (1978) and Conley (1958). These locations have not been field checked for accuracy, minerals present or for accessibility. With the help of mineral collectors, it is hoped that the occurrences below can be verified and then classified as mineral collecting sites.

    The site code (e.g., AVERY-002) refers to the site reference in the Mineral Occurrence Index.

     

    Clay County: Anorthite occurs in a dunite deposit located on Buck Creek, north of US 64 (CLAY-009).

     

     

    Potassium feldspars

     

    Microcline

     

    Chemical Composition: KAlSi3O8

    Potassium aluminum silicate

     

    Class: Silicate

     

    Crystallography: Triclinic; pinacoidal

     

    Habit: Crystals often short prismatic. Twinning may be present. Often massive, coarsely cleavable to granular.

     

    Physical properties: Luster vitreous, sometimes pearly on cleavage surfaces. Color white, gray, pale cream yellow, flesh pink, various shades of red, green (amazonstone). Streak uncolored to white. Transparent to translucent. Cleavage {001}, {010} perfect at nearly right angles (89.5o). Fracture uneven. Brittle. H. 6-6.5. S.G. 2.56-2.63.

     

    Occurrence: Microcline occurs in granites, granitic gneisses and pegmatites.

     

    Mineral localities and descriptions of localities are from Wilson and McKenzie (1978) and Conley (1958). These locations have not been field checked for accuracy, minerals present or for accessibility. With the help of mineral collectors, it is hoped that the occurrences below can be verified and then classified as mineral collecting sites.

    The site code (e.g., AVERY-002) refers to the site reference in the Mineral Occurrence Index.

     

    Caswell County: Microcline can be found in the pegmatite bodies south of Milton near Yarbro. A 10- to 12-foot wide pegmatite dike crops out (exposed) in a road cut on the north side of SR 1554, .35 mile northwest of the intersection of SR 1554 and SR 1557. The pegmatite contains near perfect crystals of microcline (CASWE-001).

    A 5- to 7-foot wide pegmatite crops out on the east-side of SR 1559, .4 mile southeast of Semora. The pegmatite is composed of intergrowths of quartz, microcline feldspar, and muscovite mica. The quartz occurs as irregularly shaped masses surrounded by subhedral to euhedral microcline feldspar and grayish to clear crystals of muscovite mica (CASWE-002). An euhedral crystal has many of its faces visible. A subhedral crystal has some of its crystal faces visible. A mineral collector tries to find perfect euhedral mineral specimens.

    Cleveland County: Microcline is one of the many minerals that can be found at the Foote Mineral Company spodumene (lithium) mine (closed) near Kings Mountain (CLEVE-013). This mine is closed to mineral collecting.

    Harnett County: Pink microcline occurs in small pegmatites at Raven Rock (an exposure of metamorphic rock) on the southwest bank of the Cape Fear River northwest of Lillington and east of Raven Rock Church (HARNE-002). Raven Rock is now part of the North Carolina Park System, which prohibits the collecting of mineral specimens.

    Henderson County: Occurs in pegmatites in the area around Tuxedo. Freeman mine, .5 mile west of Tuxedo on SR 1118 (HENDE-001) and Jones mine, .5 mile east of Tuxedo on SR 1856 (HENDE-002).

     

     

    Mineral Collecting Sites

     

    Mitchell County: Feldspar, plagioclase, quartz and mica (muscovite) occur at the McKinney mine (collecting fee charged) (MITCH-015). Other accessory minerals that occur are samarskite, garnet, autunite, torbernite, columbite, hyalite, amazonite, bornite, covellite, chalcopyrite, allanite, epidote, malachite, sphalerite and massive beryl.

    To get to the mine, take Highway 19-E west from Estatoe; at 1.3 miles turn left (south) on SR 1002; at approximately 4.8 miles turn onto SR 1100. The mine is on both sides of the road (now Emerald Village and the North Carolina Mining Museum).

    Yancey County: Feldspar (plagioclase), perthite, quartz and muscovite occur at the Ray (Wray) mica mine (abandoned) (YANCE-001). Other minerals reported are golden and aquamarine beryl, apatite crystals, clear oligoclase (plagioclase feldspar), biotite, amazonite, thulite, garnet, autunite, columbite-tantalite, tourmaline, zircon and rutile.

    To reach the mine, turn south onto NC Highway 197 from US Highway 19-E in Burnsville. Travel 0.9 mile to an intersection with SR 1109. Turn left (east) and travel along SR 1109 (Bowlens Creek Road) for approximately 1.4 miles to the intersection with SR 1192, nearly opposite the Bowlens Creek Church. Turn left (east) onto SR 1192 for about 0.3 mile where the state-maintained road ends and a 4-wheel drive road leads to mine workings a little further ahead on left. This site lies in the Pisgah National Forest.

     

    Orthoclase

     

    Chemical Composition: KAlSi3O8

    Potassium aluminum silicate

     

    Class: Silicate

     

    Crystallography: Monoclinic; prismatic

     

    Habit: Crystals often short prismatic. Twinning may be present. Often massive, coarsely cleavable to granular.

     

    Physical properties: Luster vitreous. Colorless, white, gray, pale yellow, pink, flesh red. Streak colorless to white. Transparent to translucent. Cleavage {001}, {010} perfect at right angles (90o ). Fracture uneven to conchoidal (like the edge of a glass fragment). Brittle. H. 6-6.5. S.G. 2.55-2.63.

     

    Occurrence: Orthoclase occurs in granites, granitic gneisses and pegmatites.

     

    Mineral localities and descriptions of localities are from Wilson and McKenzie (1978) and Conley (1958). These locations have not been field checked for accuracy, minerals present or for accessibility. With the help of mineral collectors, it is hoped that the occurrences below can be verified and then classified as mineral collecting sites.

    The site code (e.g., AVERY-002) refers to the site reference in the Mineral Occurrence Index.

     

    Davidson County: Orthoclase has been identified at the Silver Hill mine (abandoned) as a gangue (part of a mineral assemblage that is not profitable but must be mined to retrieve valuable ore) (DAVID-003).

    Granville County: At the Holloway mine (abandoned) located 2 miles south and 1 mile west of Virgilina in the northwestern portion of the county (GRANV-003). Copper was mined here in the late 1800’s and for short periods in the early 1900’s. Orthoclase feldspar is a gangue mineral associated with the copper ore.

    Harnett County: Orthoclase occurs in small pegmatites at Raven Rock (an exposure of metamorphic rock) on the southwest bank of the Cape Fear River northwest of Lillington and east of Raven Rock Church (HARNE-002). Raven Rock is now part of the North Carolina Park System, which prohibits the collecting of mineral specimens.

    Mitchell County: Pink orthoclase occurs at the Sullins Branch mine (active mine - no mineral collecting allowed) located 1.7 miles northwest of Spruce Pine (MITCH-009). Orthoclase feldspar which can give a sunstone sheen is found on the McKinney property, which lies at the end of SR 1159, .5 mile east of NC Highway 261, 2.4 miles northeast of Glen Ayers (MITCH-003).

     

     

    Feldspar Occurrences

     

     

    In Wilson and McKenzie (1978) and Conley (1958) the mineral feldspar is reported at a number of sites. The type of feldspar present is not known; therefore, these occurrences are lumped together under Feldspar Occurrences.

    Mineral localities and descriptions of localities are from Wilson and McKenzie (1978) and Conley (1958). These locations have not been field checked for accuracy, minerals present or for accessibility. With the help of mineral collectors, it is hoped that the occurrences below can be verified and then classified as mineral collecting sites.

    The site code (e.g., AVERY-002) refers to the site reference in the Mineral Occurrence Index.

     

    Ashe County: The Duncan mine (abandoned), 1.2 miles southwest of West Jefferson was worked for mica and also contains beryl, biotite, garnet, feldspar and quartz (ASHE-001).

    Buncombe County: Moonstone (albite or microcline) occurs at the Goldsmith mine (abandoned) (BUNCO-005). The mine is west of Democrat. To reach the site, take NC Hwy 197 west from Democrat for 0.8 mile, turn north on SR 2161 for 0.2 mile. The mine is located in an open cut on the northeast side of the road bank.

    Gaston County: The tin-spodumene belt, which extends through Gaston county, contains numerous pegmatites. Feldspar and mica are common minerals in pegmatite rocks. These pegmatites may also contain cassiterite (a tin mineral) and spodumene (lithium).

    The sites are located on the southeast corner of the intersection of SR 1401 and 1402, 1.5 miles west of Bessemer City (GASTO-006), between Little Beaverdam Creek and Beaverdam Creek on SR 1624, in a road cut on a divide between the creeks (GASTO-001 and GASTO-002), and in road cuts north of the junction of Beaverdam Creek and SR 1620 (GASTO-003 and GASTO-004). Another uranium-bearing pegmatite with feldspar and mica occurs in a road cut exposed on NC Hwy 216, north of its intersection with SR 1409 (GASTO-005).

    Jackson County: Plagioclase occurs in pegmatites at the Sheepcliff mine (abandoned), 3 miles north of Cashiers (JACKS-002).

    Macon County: Moonstone is reported at the Rose Creek Star Garnet Mine (collecting fee charged) (MACON-004) and at Mason Mountain Rhodolite Mine (collecting fee charged) (MACON-007).

    Madison County: Unakite, a metamorphosed granite rock composed of epidote, pink feldspar (orthoclase?) and quartz is reported on Roaring Fork Creek, a short distance above its entrance into Meadow Creek, 2.8 miles southwest of Bluff (MADIS-006). Unakite is also reported to occur just north of Bluff (MADIS-007).

    Mitchell County: Feldspar and mica, along with beryl, apatite, hyalite, cyrtoite, uraninite, autunite, torbernite and gummite, occur at the Old 20 mine (abandoned) located southwest of Spruce Pine, on the west side of the road to Little Switzerland (MITCH-014).

    Randolph County: Feldspar is reported at an abandoned highway quarry on the east side of SR 1411, 0.6 mile north of the intersection Hwy 64 and SR 1411 (RANDO-001).

    Swain County: Feldspar (plagioclase) was mined at the Cox No. 1 mine (abandoned) (SWAIN-001) (Cameron, 1951, p. 82-85 and plate 1 and 17). Perthite, microcline feldspar with intergrowths of albite, was mined along with plagioclase feldspar at the Carson mines (abandoned) (SWAIN-002). (Cameron 1951, p. 51-56, plate 1 and plate 5).

    Yancey County: Feldspar was mined from many pegmatites in the county. A few of these are: Presnell mine (abandoned), located on the Toe River 2 miles north of Micaville (YANCE-005); Old Charles mine (abandoned), located 2.4 miles northeast of Micaville (YANCE-006); Fanny Gouge mine (abandoned), which lies 2.5 miles southeast of Micaville (YANCE-007); and the Spec (Speck) mine (abandoned) (YANCE-008), which is said to be located south of the Fanny Gouge mine. Lesure (1968) places the Speck mine northeast of the Fanny Gouge mine.

     

     

    References

     

    Carpenter, R.H., Schlanz, J.W. and Carpenter, P.A., III, 1995, Potential feldspar resources in north-central North Carolina: North Carolina Dept. of Environment, Health and Natural Resources, North Carolina Geol. Sur., Open-File Report 95-1, 21 p.

     

  • Bourne, H.L., 1994, Glass raw materials: in Carr, D.D. and others, eds., Industrial minerals and rocks (6th edition): Littleton, CO, Soc. for Mining, Metallurgy and Exploration, Inc., p. 543-550.
  • Conley, J.F., 1958, Mineral localities of North Carolina: North Carolina Dept. of Natural and Economic Resources, Div. of Earth Resources, Geology and Mineral Resources Section, Information Circular 16, 128 p.

     

    Cook, R.B., 1978, Minerals of Georgia, their properties and occurrences: Georgia Dept. of Natural Resources, Geology and Water Resources Div., Bull. 92, 189 p.

     

    Dana, E.S., 1952, Dana's Manual of Mineralogy: John Wiley and Sons, New York, 530 p.

     

  • Kauffman, R.A. and Van Dyk, D., 1994, Feldspars: in Carr, D.D. and others, eds., Industrial minerals and rocks (6th edition): Littleton, CO., Soc. for Mining, Metallurgy, and Exploration, Inc., p. 473-481.
  • Lesure, F.G., 1968, Mica deposits of the Blue Ridge in North Carolina: U.S. Geol. Sur. Prof. Paper 577, 129 p.

     

    Neal, P.J., Wiener, L.S., Carpenter, P.A., III, Wilson, W.F. and Parker, J.M., III, 1973, Evaluation of potential North Carolina feldspar resources: Report MRL-3, Minerals Research Laboratory, School of Engineering, North Carolina State University, 67 p.

     

    Paris, T.A., 1994, Minerals of Tennessee: privately printed, 240 p.

     

    Potter, M.J., 1991, Feldspar, and Nepheline Syenite, and Aplite: Annual Report, US Dept. of Interior, US Bureau of Mines.

     

    Potter, M.J., 1996, Feldspar and Nepheline Syenite: Minerals Yearbook, US Dept. of Interior, US Geological Survey; (//minerals.er.usgs.gov/minerals).

     

    Potter, M.J., 1997, Feldspar: Mineral Commodity Summaries, US Dept. of Interior, US Geological Survey; (//minerals.er.usgs.gov/minerals).

     

    Reid, J.C., Carpenter, R.H. and Davis, T.E., 1999, Permitted active and inactive mining operations in North Carolina as of June, 1998: North Carolina Dept. of Environment and Natural Resources, Open-File Report, in preparation.

     

    Stuckey, J.L., 1965, North Carolina: Its geology and mineral resources: North Carolina Div. of Mineral Resources, 550 p.

     

    Watts, A.S., 1913, Mining and treatment of feldspar and kaolin in the southern Appalachian region: U.S. Bur. of Mines Bull. 53, 170 p.

     

    Wiener, L.S. and Merschat, C.E., 1977, Field guidebook to the geology of the central Blue Ridge of North Carolina and the Spruce Pine Mining District: Assoc. of Amer. State Geologists, Ann. Meeting, May 1975, Asheville, North Carolina, North Carolina Dept. of Natural and Economic Resources, Div. of Earth Resources, Geology and Mineral Resource Sec., 24 p.

     

    Wilson, W.F. and McKenzie, B.J., 1978, Mineral collecting sites in North Carolina: North Carolina Dept. of Natural Resources and Community Development, Geol. Sur. Sec., Information Circular 24, 122 p.