MORPHOLOGY & MINERALOGY OF
WATER DISPERSIBLE SAND & SILTS

List of SEM Figures

  1. Organic matter morphologies of organics retaining some plant morphology. a. From the Kirkland soil. b. From the Sharkey soil. c. From Humatas soil. d. From the Nipe soil.
  2. Organic matter morphologies. a. Filamentous organics from the Humatas soil. b. Organic filaments on a quartz grain from the Orangeburg soil. c. Sheet morphology of organic matter from the Consumo soil. d. Folded sheet morpholo gy and partially decomposed organic matter with quartz grains from the Cecil soil. Arrows point to organic debris.
  3. Calcite morphologies from the Heiden soil. a. Fossil shell with coating of recrystallized calcite. b. Coccolith fossil. c. Botryoidal calcite. d. Mixture of bladed and other non-fossil forms of calcite. e. Calcite covered surf ace with linear striations and small crystals on surface. f. Group of fossils (arrows) including disk shaped coccoliths along with bladed calcite and quartz.
  4. Aggregates which were never dispersed. All are from the Hayesville soil. a. Aggregate high in Fe and Al. b. Fe oxide dominated aggregate. Note the dendritic form of Fe oxide on the sand grain (arrow). c. Sandy aggregate hi gh in Al and Fe. d. Closeup of hole in (c) rotated for better view of internal void.
  5. Aggregates formed by grains which were initially disaggregated but which failed to maintain dispersion. a. Example from the Kirkland soil. Feldspar is shown at arrow. b. From the Memphis soil. c. From the Maury soil. d. From the Sharkey soil.
  6. Clay coatings. a. Sand grain with a thick Fe oxide coating from the Marlton soil. b. Closeup of the surface of (a) showing the platy morphology of the coating. c. Clay coated sand grain from the Memphis sample. d. Closeup of (c) showing the platy nature of the adhered clay.
  7. Lithorelicts. a. Glauconite grain from the Marlton sample. b. Closeup of (a) showing the platy morphology. c. Serpentinite fragment from the Nipe clay. d. Schist fragment from the Cecil soil.
  8. Quartz morphologies from residual soils. a. Crystal with slightly rounded faces from the Cecil soil. b. Compound grain from the Wayah soil. c. Quartz grain from the Hayesville soil. d. Another grain from the Hayesville soil.
  9. Quartz morphologies from soils with sedimentary parent material. a. Grains from the Memphis soil showing morphologies of a loess source. b. Grain from the loessal Memphis soil showing many conchoidal fractures. c. Rounded gra ins from the Ocala sample showing the effects of rounding during transport by water. d. Grain from the Boonville soil where the water rounding is partially obscured by overgrowths.
  10. Other forms of SiO2. a. Thick quartz overgrowth broken off of weathered grain in Decatur Bt. b. Unusual morphology for SiO2 from Consumo A sand. Aggregate on left, plant opal or crystobalite (more likely) on right. c. Unusu al surface morphology on SiO2 grain. d. Unusual SiO2 morphology of 3-4 composite grains; Composite aggregate at upper right is mostly Si with small Al peak.
  11. Phytoliths. a. Relatively fresh phytolith from the Nipe soil lying on Fe oxide grain with organic filament. b. Extremely weathered plant opal from the Foley Ap. c. Weathered plant opal from Consumo B. d. Second weathered phyt olith from the Consumo B.
  12. Accessory minerals. a. Kyanite or sillimanite from the Cecil soil. b. Ilmenite from the Humatas soil. c. Gibbsite appearing to have grown outward into a pore in the Hayesville soil. d. A weathered Ti oxide grain with crystall ographic etch pits and an Fe oxide coating.
  13. Weathered feldspars from the Wayah soil. a. Anorthite grain with bands. b. Very weathered zoned plagioclase grain. c. Extremely etched plagioclase grain. d. Closeup of the grain shown in (c).
  14. Apatite and iron oxides morphologies. a. Apatite crystal from the Maury soil showing crystal faces suggesting that weathering of apatite is not intense in the soil. b. Apatite grain from the Heiden soil showing extensive weat hering. c. Fe oxide grain from the Maury Bt horizon showing crystal faces. d. Fe oxide grain from the Maury Bt horizon showing crystal faces.
  15. Contrasting fresh (a and b) and highly etched (c and d) quartz sand grains from the Decatur soil.
  16. Phyllosilicate morphologies. a. and b. Kaolinite vermiforms from the Humatas soil. c. A muscovite grain with frayed edges from the Wayah soil. d. Biotite crystals from the Hayesville soil.
  17. Mineral grains from the Alachua Bh sample. a. Kaolinite vermiform. b. Kaolinite vermiform at right using a delaminated muscovite grain as a template for crystal growth. c. Iron oxide coated TiO2 grain (arrow). Other grains a re quartz except for a small grain of kaolinite near bottom center. d. Kyanite (Al2SiO5) crystal.
  18. Soil particles from the Alachua Btg sample. a. Opal phytolith. b. Kyanite grain (elongated crystal at center) with other grains.
  19. Morphology of soil particles from the Boonville soil. a. Weathered feldspar grain showing crystallographically controlled dissolution features. b. Relatively fresh Na plagioclase grain at top with opal phytolith at lower le ft (arrow).
  20. Aggregates from the Decatur soil.
  21. Features of the Foley soil. a. Aggregate from the Ap of organic sheets and mineral grains. b. Broken feldspar grain (arrow) from the Ap horizon showing grain rounding from water transport.
  22. Grain morphologies from the Hayesville soil. a. Highly etched quartz grain from the Ap horizon. b. High Fe mica (biotite) from the C2 horizon.
  23. Mineral grains from the Kirkland soil. a. Potassium feldspar sand grain. b. Intermediate Na-K feldspar grain rounded from water transport but still showing cleavage features. c. Quartz grain which appears to have had a comple x history of overgrowths. The flaky material at the center of the grain is adhered dioctahedral mica. d. Rounded TiO2 grain.
  24. Mineral grains from the Marlton soil. a. Relatively unweathered compound quartz grain. Note the adhered grains common to most quartz from this soil. b. Coated grain with obvious grain contact scar formed by the coating bridg ing between two grains (arrow).
  25. Minerals of the Maury soil. a. Apatite grain from the Ap horizon. b. Partially decomposed organic matter from the Ap horizon. c. Anatase crystal from the Ap horizon. d. Uncoated quartz grain from the Bt horizon.
  26. Mineral grains from the Memphis soil. a. Quartz grain showing conchoidal fracturing consistent with loess. b. Rare highly etched weatherable mineral grain.
  27. Minerals from the Ocala National Forest sample. a. Crystal of TiO2. b. Pollen grain which has been replaced by SiO2 and weathered.
  28. Features from the Orangeburg soil. a. Rounded quartz grains characteristic of water deposited sediments. b. Aggregate of rounded quartz grains and organic material.
  29. Minerals of the Sharkey soil. a. Calcite fossil (?) in the form of a hexagonal tube. b. Weatherable ferromagnesian mineral grain.

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Last Modified: November 24, 1998

Document Prepared by:
North Carolina Agricultural Research Service
North Carolina State University