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Bikitiate Slideshow

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  • 1. BIKITAITE FROM THE FOOTE MINE, CLEVELAND COUNTY, PIEDMONT OF SOUTHERN NORTH CAROLINA Donald R. Privett S.T.A.R. Environmental 1 Circle Street Great Falls, S.C. 29055 [email_address]
  • 2. Unusually large euhedral prismatic crystals (up to 2.8 cm long) and intergrown crystal aggregates (ICA) of bikitaite (Li 2 Al 2 Si 4 0 12 .2H 2 0 ) were discovered in an exposed nearly vertical yellow-orange plastic clay filled druse about one meter long, 10-12 cm wide and 0.8 m deep.
  • 3. These crystals are larger than those from Bikita, Zimbabwe; the only other known occurrence. X-ray diffraction and optical properties are very similar to bikitaite from Zimbabwe.
  • 4.  
  • 5. Located in the Kings Mountain Belt, just off Interstate 85 and Dixon School Road, a complex of meta-igneous and meta-sedimentary rocks extends for at least 80 km from the Catawba River on the north to the area south of Gaffney , South Carolina.
  • 6. Spodumene pegmatite (Mississippian)— White, medium- to coarse-grained, and generally unzoned pegmatite. Composed of spodumene, microcline, quartz, albite, and muscovite. Trace amounts of beryl, manganapatite, ferrocolumbite, cassiterite, and zircon are present. Secondary minerals such as vivianite, fluorapatite, and siderite occur in fractures and vugs. Only spodumene and microcline commonly exceed 2 cm in size, which defines a pegmatite; these crystals are rarely longer than 30 cm. Spodumene and microcline are commonly fractured and the fractures are filled with a sugary matrix of albite and quartz. Yellowish-white muscovite crystals, commonly twisted, are typically less than 2 cm long. Whole-rock Rb-Sr age is 340 ± 10 Ma (2 σ ) (Kish and Fullagar, 1996). Pegmatites occur as dikes and sills in a narrow belt in and just west of the Kings Mountain shear zone, and are most abundant in and near bodies of amphibolite. Pegmatites range from nonfoliated to strongly foliated, and locally crosscut foliation in the Kings Mountain shear zone. Locally, particularly near wall-rock contacts, blastomylonitic or augen-gneiss texture is developed. From Horton, J.W., Jr., 2008, Geologic map of the Kings Mountain and Grover quadrangles, Cleveland and Gaston Counties, North Carolina, and Cherokee and York Counties, South Carolina: U.S. Geological Survey Scientific Investigations Map 2981, 1 sheet, scale 1:24,000, with 15-p. pamphlet.
  • 7. Single crystals collected from duse.
  • 8.  
  • 9. Intergrown crystals.
  • 10. Intergrown crystals on fragmeted pegmatite in the druse, albite?crystallized on the pegmatite.
  • 11. Single crystals at bottom of druse probably broken from sides of druse covered by tan plastic clay.
  • 12. Densely inter-grown crystals.
  • 13.  
  • 14.  
  • 15. Broken crystals on top of pegmatite fragment.
  • 16. Matrix of broken interpenetration crystals. Scale in cm.
  • 17. Clusters-Most broken off left, right mos intact. Sccale in cm.
  • 18.  

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