Fieldwork was carried out by a team of DMR and BGS geologists in 1996 with the aim of compiling an inventory of diatomite deposits in Changwat Lampang. Detailed lithological logs of major quarry sections were prepared. At each quarry, \"spot\" samples were collected at 0.5 m stratigraphic intervals and larger \"laboratory\" samples were also collected from the main diatomite beds. Diatomite quality was assessed mainly by physical analysis of the \"spot\" samples (block density, specific gravity, porosity, moisture content), supplemented by major-element chemical analysis of the larger \"laboratory\" samples. Results indicate that sedimentary features observed in the field (clay content, Fe-staining, discrete clay beds, bedding lamination, clay- and Fe-filled burrows, etc.) are responsible for marked variations in physical and chemical properties. Because of this heterogeneity, it was possible to classify intervals within the diatomite sequence as either \"high quality\" of \"low quality\" on the basis of defined physical and chemical criteria.
The main objective of the diatomite inventory was to identify sources of diatomite in Thailand for use in the treatment of contaminated land. However, it is emphasised that the approach to the assessment of diatomite resources outlined in this report is generic and could be adopted by Geological Surveys/Mines Departments in other countries for primary classification of their diatomite deposits.
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