Determine the Presence of Gold and its Distribution in Upper Nilwala River Basin, Southern Part of Sri Lanka
No Thumbnail Available
Date
2015
Journal Title
Journal ISSN
Volume Title
Publisher
Uva Wellassa University of Sri Lanka
Abstract
Gold (Au) is a chemical element, bright yellow dense, soft, malleable and ductile metal. The
properties remain when exposed to air or water. It occurs often in free elemental (native) form,
as nuggets or grains, in rocks, in veins and in alluvial deposits.
Investments made on gold prospecting are only second to oil exploration. This research was
carried out to find gold in upper Nilwala River and possible areas that gold can be found. In this
study, distributions of indicator elements of gold were studied to identify potential gold
enrichments in the upper Nilwala River Basin.
Stream sediment samples were collected mainly from the placer deposits see figure 1. Samples
were taken at about 1 –2 feet depth on placer deposit or river bed by using a shovel. Also gem pit
sediment samples were collected near to the gem bearing layer. Samples were collected using the
hand pit method (Fletcher et al., 1997). A total of 1–2 kg of raw samples was taken from each
location. Then all samples were transferred to neatly labeled polyethylene bags. About 1 kg of
sediment samples were separated by using cone and quarter method. Then heavy sediments of it
were separated by panning method . Then it was dried in a hot air oven. Each sample was stored
in a labeled sample bags to use for mineralogical analysis carried out using an optical microscope.
From remaining dried 1 kg samples were homogenized and near 100 g of samples were again
separated using cone and quarter method. Then separated sample fractions were crushed by using
vibrating cup mill to less than 63 µm.
Optical microscope was used to identify the minerals occur in the heavy sediment sample. Using
corn and quarter method substantial amount of heavy sediments were separated for the testing.
Using a magnet all the magnetic minerals of the sample was separated. 5X5 equal squares were
marked on the glass slid. Then glycerol liquid was applied on the top of that slid. After that heavy
sediments were put on to the slid creating a fine layer. Finally both magnetic and nonmagnetic
minerals were analyzed. Couples of samples were selected. Magnetic separation was done for
those samples. Then for the nonmagnetic section Bromoform test was done. Then the heavy
particles were separated. After that the samples were analyzed using an optical microscope.
The grinded sediments (<63 µm) were tested using X-ray florescence spectroscopy (XRF) to
identify chemical composition and major elements for each sample.
Description
Keywords
Mineral Sciences, Materials Sciences, Mineral, Science and Technology, Gold, Geochemistry, Geographic