Llano County
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Albite (Sodium Feldspar), Llano County, Texas
Albite Crystals Locality: Badu Hill Pegmatite, Llano County, Texas Albite is a Plagioclase Feldspar, a Sodium Silicate Chemical Formula: NaAlSi3O8 Crystal System: Triclinic Specimen dimensions: 3.25"x2.25"x2" Specimen Weight: 145 grams In the Arthur E. Smith Collection, on display at Wheaton College, Wheaton, Illinois.
Gadolinite (Y), a Berylium Yttrium Rare Earth, Llano County, Texas
Gadolinite Locality: Llano County, Texas (Baringer Hill) Chemical Formula: Y2FeBe2Si2O10 Crystal System: Monoclinic Specimen size: 3 x 3.25 x 2 inches Specimen weight: 742 grams In the Jackson School of Geosciences Collection, University of Texas at Austin. Collection reference: TMM 1875. Additional Information: Baringer Hill is the site of a pegmatite, discovered in 1887 by John Baringer, and has been described by the USGS as one of the greatest deposits of rare-earth elements in the world. Unfortunately, the site is now covered by the waters of Lake Buchanon. So this sample is rare, and even though it doesn't display the crystal forms found in Norway and Italy, it does display the characteristic glassy vitreous nature and brittleness and conchoidal fractures that are common in specimens.
Microcline, Llano County, Texas
Microcline, a Potassium Feldspar Locality: Badu Hill Pegmatite in Llano County, Texas Chemical Formula: KAlSi3O8 Crystal System: Triclinic Specimen size: 4 in x 2.5 in x 2 in Specimen weight: 216 grams In the Arthur E. Smith Collection, on display at Wheaton College, Wheaton, Illinois. Additional Information: The Badu Hill Pegmatite, discovered in 1936 by Tillie Badu Moss, is a late-stage hydrothermal pegmatite located about 4 miles southwest of Lake Buchanan, in Llano County. Classified as an NYF or "rare-earth" pegmatite, Badu Hill contains a large number of rare-earth minerals, many of which are radioactive due to the presence of uranium and thorium daughter elements.
Allanite closeup, Llano County, Texas
Allanite (also called Orthite) Locality: Rode Ranch Pegmatite, Llano County, Texas Allanite is a Sorosilicate, often containing rare earth elements. Chemical Formula: (Ce,Ca,Y,La)2(Al,Fe+3)3(SiO4)3(OH) Crystal System: Triclinic In the Arthur E. Smith Collection, Wheaton College, Wheaton, Illinois.
Fergusonite and Gadolinite, Llano County, Texas
Gadolinite is a rare earth Nesosilicate In photo, the darker, black mineral Chemical Formula: Y2FeBe2Si2O10 Crystal System: Monoclinic - Prismatic Fergusonite is a complex oxide of various rare earth elements In photo, the greenish fractured masses Chemical Formula: (Y,RE)NbO4, where RE is rare earth in solid solution with Y Crystal System: Tetragonal - Dipyramidal Locality: R. A. Rode Ranch Pegmatite, Llano County, Texas Specimen size: 4.5 in x 3 in x 3 in Specimen weight: 666 grams In the Arthur E. Smith Collection, Wheaton College, Wheaton, Illinois. Additional Information: These minerals were found on a ranch 23 miles from the famous Baringer Hill pegmatite, locality renowned for many rare earth minerals.
Tremolite, Llano County, Texas
Tremolite, a fibrous Amphibole, also referred to as Asbestos Chemical Formula: Ca2(Mg5.0-4.5Fe0.0-0.5)Si8O22(OH)2 Crystal System: Monoclinic Specimen Size: 3.25 in x 2 in x 1 in Specimen Weight: 76 grams In the Arthur E. Smith Collection, on display at Wheaton College, Wheaton, Illinois. Additional Information: In addition to this Tremolite asbestos from the Precambrian metamorphic rocks of the Llano region, amphibole asbestos is also associated with talc deposits in Hudspeth County.. No asbestos is mined in Texas.
Amethyst (SiO2), Llano County, Texas
Locality: Amethyst Hill (?), Llano County, Texas Purple quartz of this quality are rare in the Hill Country Chemical Formula: SiO2 (its violet color to irradiation, iron impurities, and the presence of trace elements) Crystal Class: Hexagonal (Most often as protruding clusters of pyramids on a matrix base, often quite large. Also occurs as tall prismatic crystals, and as short stubby crystals, in drusy aggregates Size: 12.5cm x 5cm x 10 cm Weight: 732 grams Personal Collection of Professor Dr. Mark Helper, Univ. of Texas at Austin
Garnet, Llano County, Texas (Badu Hill Pegmatite)
Garnet, probably Spessartine variety Locality: Llano County, Texas (Badu Hill Pegmatite) Chemical Formula: Mn3Al2Si3O12 Crystal System: Isometric, this sample a classic modified dodecahedral Specimen size: 2.5 in x 2.5 in x 2.5 in Specimen weight: 144 grams In the Arthur E. Smith Collection, Wheaton College, Wheaton, Illinois. Additional Information: The Badu Hill Pegmatite, discovered in 1936 by Tillie Badu Moss, is a late-stage hydrothermal pegmatite located about 4 miles southwest of Lake Buchanan, in Llano County. Classified as an NYF or "rare-earth" pegmatite, Badu Hill contains a large number of rare-earth minerals, many of which are radioactive due to the presence of uranium and thorium daughter elements.
Uraninite in Biotite, Llano County, Texas
Uraninite , a Uranium Dioxide decaying (yellow brown stains) in Biotite Mica Locality: R.A. Rode Ranch Pegmatite in Llano County, Texas Uraninite Chemical Formula: UO2 Uraninite Crystal System: Isometric, hexoctahedral Biotite Chemical Formula: K(Mg,Fe)3AlSi3O10(F,OH)2 Biotite Crystal System: Monoclinic, brittle micaceous perfect cleavage Specimen Size: 2.5 in x 2.5in x 0.5 in Specimen Weight: 46.8 grams In the Arthur E. Smith Collection, on display at Wheaton College, Wheaton, Illinois. Additional Information: This sample was collected on a ranch 23 miles from the famous Baringer Hill pegmatite, locality renowned for many rare earth minerals.
Fergusonite (green), a Yttrium Niobium Rare Earth, Llano County, Texas
Locality: from the Baringer Hill Pegmatite, Llano County, Texas Fergusonite is a complex oxide of various rare earth elements Chemical Formula: (Y,RE)NbO4, where RE = rare earth Crystal System: Tetragonal - Dipyramidal Specimen Size: 3 in x 3.5 in x 2.75 in Specimen Weight: 918 grams Specimen Identification: TMM-2290 In the Permanent Collection of the Jackson School of Geosciences, the University of Texas at Austin. The pegmatite was discovered in 1887, but buried under Lake Buchanon in 1937.
Llanite (or Llanoite), Llano County, Texas
Llanite is an intermediate grain size Rhyolite, noted for its unusual coloration consisting of bright blue quartz and orange phenocrysts of microcline set in a fine grained grey to dark matrix Locality: outcrops along Texas State Highway 16 north of Llano, Texas Mineralogy: Quartz, microcline and plagioclase feldspars, biotite, fluorite, apatite and traces of magnetite, ilmenite and zircon Specimen size: 5.5 in long x 2-4 in wide x .375 in thick Specimen weight: 160 grams Shared by the Downs Collection (UT).
Vesuvianite, Llano County, Texas
Vesuvianite, a sorosilicate found in skarns (contact metamorphism of limestones) Location: specific unknown County: Llano County, Texas Chemical Formula: (Ca,Na)19(Al,Mg,Fe3+)13(B,Al,Fe3+)5(Si2O7)4(SiO4)10(OH,F,O)10 Crystal System: Tetragonal Specimen size: 4 x 2.75 x 1.5 inches Large Crystal highlighted: 1 inch long x .75 x .75 inches Specimen weight: 630 grams Collection Reference: TMM 1272. In the Jackson School Collection at the University of Texas at Austin.
Gadolinite (Y), a Berylium Yttrium Rare Earth, Llano County, Texas
Gadolinite Locality: Llano County, Texas (Baringer Hill) Chemical Formula: Y2FeBe2Si2O10 Crystal System: Monoclinic Specimen size: 1.75 in x 1.25 in x .75 in Specimen weight: 43 grams In the Arthur E. Smith Collection, Wheaton College, Wheaton, Illinois. Additional Information: Baringer Hill is the site of a pegmatite, discovered in 1887 by John Baringer, and has been described by the USGS as one of the greatest deposits of rare-earth elements in the world. Unfortunately, the site is now covered by the waters of Lake Buchanon. So this sample is rare, and even though it doesn't display the crystal forms found in Norway and Italy, it does display the characteristic glassy vitreous nature and brittleness and conchoidal fractures that are common in specimens.
Magnetite (Iron oxide), Llano County, Texas
Iron Ore (highly magnetic) Location: Iron Mountain (at 30°51' N, 98°54' W). County: Llano County Chemical Formula: Fe(2+) Fe2 (3+) O4 Crystal System: Isometric Specimen Size: 3.5 x 1.25 x 2 inches Specimen weight: 602 grams In the Jackson School Collection at the University of Texas at Austin. Collection Reference: TMM 1509 Additional Information: Smoothing Iron Mountain, also known as Iron Mountain, stands four miles west of the town of Valley Spring in northwestern Llano County (at 30°51' N, 98°54' W). It is the location of perhaps the largest iron ore deposit in the state. Although not the foundation for a significant Texas iron industry that some promoters had anticipated, this deposit has been mined several times, most recently in the 1930s. At an elevation of 1,839 feet, the mountain rises approximately 520 feet above nearby Cold Creek.