Goethite Morphologies Investigated Via X-Ray Diffraction of Oriented Samples

Ford, Robert G.; Bertsch, Paul M.; Seaman, John C.

doi:10.1346/ccmn.1997.0450515

Cited by 16 publications

(9 citation statements)

References 17 publications

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“…On the other hand, the cavity arrangement of honeycomb crystallization also illustrates that birnessite consists of radiating rods as described by Burns and Burns (1977) and Lonsdale et al (1980). Golden et al (1988) also observed the platy micromorphology of synthetic birnessite. The typical rapid, special variation of irregular platy crystal sizes, shape of aggregation ( Figure 4C), and low peak intensities (Figure 2) explain the poor crystallinity of birnessite.…”

Section: Micromorphology Of Fe/mn and Their Associated Mineralssupporting

confidence: 60%

“…The detailed morphology of goethite also shows that the shape of individual goethite crystals is grass-leaf like and these acicular goethite particles are rare (Schwertmann and Kampf, 1988), but typically form in poorly drained soils (Schwertmann and Taylor, 1989). Goethite particles produced in the presence of high Al concentrations in Fe/Mn concretions are more equidimensional and do not orient well (Ford et al, 1997).…”

Section: Micromorphology Of Fe/mn and Their Associated Mineralsmentioning

confidence: 95%

“…The crystal shape of synthetic goethite in alkaline conditions is usually acicular and often consists of several domains within the crystal along the needle axis (Schwertmann and Taylor, 1989;Ford et al, 1997).…”

Section: Micromorphology Of Fe/mn and Their Associated Mineralsmentioning

confidence: 99%

“…This simple step was useful for dissolving Mn and Fe oxides, separately and for determining the respective metal ions that were released. Tokashiki et al (1986) and Golden et al (1993) combined selective dissolution procedures with XRD analysis. In their studies, concentrated NaOH was used to dissolve kaolin minerals and hydroxylamine hydrochloride was used to distinguish birnessite from Fe oxides.…”

Section: Introductionmentioning

confidence: 99%

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Mineralogical characteristics and micromorphological observations of brittle/soft Fe/Mn concretions from Okinawan soils

Arachchi

Tokashiki

Baba

2004

Clays and clay miner.

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Manganese minerals are not common and the distinction of poorly crystalline Mn minerals from other associated minerals is important. For many years, the crystal structures of poorly crystalline Mn minerals in Fe/Mn concretions have been the subject of considerable conjecture and controversy. This study reports the micromorphological and mineralogical characteristics, and the chemical composition of Fe/Mn minerals in soft Fe/Mn concretions formed in Shimajiri Mahji soils (Typic Hapludalfs) that developed from Ryukyu limestone on Okinawa Island, Japan. The Fe/Mn minerals in brittle/soft Fe/Mn concretions were characterized using a sequential selective dissolution procedure (SSDP) by treatments with NaOH, hydroxylamine hydrochloride (HAHC) at 25ºC and 60ºC, and dithionite-citrate-bicarbonate (DCB) in combination with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The HAHC treatment at 25ºC dissolved birnessite, but not lithiophorite and goethite. A subsequent extraction with HAHC at 60ºC dissolved lithiophorite but not goethite. Finally, the DCB treatment was able to dissolve goethite. The SEM images show that birnessite crystals, with a blade-or plate-like habit, form globular aggregates inside veins and cavities. Pseudo-hexagonal crystals of lithiophorite have produced thread-ball structures with crystal shape similar to birnessite and birnessite crystals are closely associated with lithiophorite. Well developed hexagonal plates of gibbsite crystals are clustered in different directions to make foliated vermiform structures. Aggregates of goethite crystals are acicular and are arranged into stars. The supplementary SSDP, in combination with XRD and SEM techniques, provides methods to distinguish and partly quantify birnessite and lithiophorite in the presence of layer silicate and Fe oxide minerals and confirm their own morphological features.

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Section: Micromorphology Of Fe/mn and Their Associated Mineralssupporting

confidence: 60%

Section: Micromorphology Of Fe/mn and Their Associated Mineralsmentioning

confidence: 95%

Section: Micromorphology Of Fe/mn and Their Associated Mineralsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mineralogical characteristics and micromorphological observations of brittle/soft Fe/Mn concretions from Okinawan soils

Arachchi

Tokashiki

Baba

2004

Clays and clay miner.

View full text Add to dashboard Cite

show abstract

“…Aside from preferred orientation effects and line broadening in powder X-ray diffraction methods [9], no major effects on the bulk characterization of goethite have been reported resulting from morphological differences in goethite crystals. Variations in crystal size evidently affect the specific surface area of the resulting goethite particles, among other characteristics, and a range between 8 and 200 m 2 /g has been reported [1].…”

Section: Introductionmentioning

confidence: 99%