Structural and Geochemical Characteristics of Limonite ore in Dela Sri Lanka
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Date
2013
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Uva Wellassa University of Sri Lanka
Abstract
Limonite (FeO.OH (H2O)) is hydrated, amorphous, and non-crystalline form of iron oxide.
Limonite contains around 52.86% of iron. In Sri Lanka hydrated iron oxide is present as
boulders, hill capping and near-surface deposits, classified as supergene deposits, around Dela-
Noragolla (Jayawardena, 1984).
The objective of this research is to identify the chemical compositions, weathering grade,
weathering pattern, decomposition, and provenance of Dela Limonite. There are only a limited
number of detailed geochemical and mineralogical studies carried out up to date. Therefore,
present research focuses on filling the gap in knowledge by identifying geochemistry with
mineralogical characteristics of the limonite deposit. Each sample was homogeneously crushed. Fresh crushed samples were powdered using mortar and pestle and sieved into < 63 µm
size.
wave number. The most representative limonite sample (SLDL 01)
was analyzed at 25 °C room temperature, obtained with 2Th/Th radiation, operating at 40 kV,
30 mA and diffraction data were compared with references. XRF analysis was carried out using
Brucker hand held XRF S1 TITAN instrument for forty (40) selected major and trace elements
by having 0.4008 average errors.
Results and Discussions
,
1100 cm , and 800 cm wave numbers showing water group, P-H bond, organic sulfate, P=O
and silicate iron (Coates, 2000; Stringfellow et al, 1993). In XRD analysis minerals were
verified as limonite, goethite, quartz and hematite present in the deposit. Measured XRF data
are summarized in Figure 2. By comparing with UCC value, it was clearly identified that the
Fe2O3, P2O5, and MnO are enriched in this deposit (Figure 3). MgO, TiO2, Cl, Co, and Ce
slightly deviate from the UCC value. Al2O3, SiO2, K2O, CaO, S, V, Cr, Cu, Zn, Rb, Sr, Y, Sn
have fewer amounts compared to the UCC value.
Less amounts of Al2O3, SiO2, K2O, and CaO represent that insignificant amount of feldspar.
Low percentage of silica in the deposit revealed that the rock formation was in mafic
environments. Having very fewer amount of S and Chalcophile elements trace elements
represent that there is no sulphide mineral is a source to form this deposit.
Geochemically Ce, and Y are the traces, which were representing formation of apatite as a
heavy mineral. By enrichment of P2O5, and fewer amount of Ca, Cl, OH, Ce and Y indicated
that the apatite was present as a gangue mineral in this deposit.
Description
Keywords
Mineral Sciences, Materials Sciences, Mineral, Geochemistry, Geochemical, Science and Technology