Exploration of clays suitable for the manufactoring of porous brick products in the area of Bom ev Breg, Gori ko (Slovenia)

In 1992, exploration of clays suitable for the manufactoring of porous brick products was conducted in two phases in the area of Bom ev Breg, Gori ko. In the course of the first phase, at the beginning of the year 1992, geological prospecting of sediments (mostly clays and clayey sands) of the Upper Triassic to Pliocene age was conducted in Gori ko, precisely in the area between Grad and Kuzma. The objective of this phase was to identify narrow areas with the deposits of clays suitable for the manufacturing of porous brick products. The area of Bom ev Breg was singled out as a perspective ground for further exploration and drilling (Figure 1).On the basis of the results obtained during the first phase of the exploration detailed geological exploration, which included drilling and partial laboratory investigations of clay, was conducted in May and June 1992. During this phase nine boreholes of a total length of 150 m were drilled (Figure 3).Samples of clay were taken from each core, and laboratory tests, mostly swelling, were carried out in controlled environment by LECA, Ges.m.b.H from Fehring, Austria.On the basis of data obtained from borehole drilling and interpretations of geological sections it can be summarized that the following three lithological types can be identified in the area of Bom ev Breg:-dark brown, brown, light brown, grey brown and greyish, in places speckled, silty fine sand and mica clay-olive greyish, fine silty and mica, partly plastic, clay-brown (limonitized), light brown and greyish clayey sand, containing silt and mica, in places with rare quartz pebbles, not more than 12 mm in diameterThe transition from one lithological type to another is not sharp but rather gradual with the exception of sandy beds where the transition is more distinct.During the prospecting phase in the area of Bom ev Breg 10 samples, marked B-1 to B-10, were taken from the boreholes drilled in the form of a mesh, 100 x 100 m, and 1 sample, marked BR-3, was taken for x-ray testing (Figure 2).The x-ray test of the sample marked BR-3 showed the following composition: muscovite / illite 32 %, chlorite 24 %, Ca-montmorillonite 11 %, quartz 17 %, plagioclase 7 %, microcline 5 %, goethite 3 %, while calcite content was under the limit of determination.The mineral resource was named clay of an illite – montmorillonite type.Based on the results of an expansion of burned samples test on samples B-1 to B-10 at 1180o C it can be summarized that mass volume of expanded balls with an addition of 0,5 % of oil is between 0,377 g/cm3 in B-1 and 0,700 g/cm3 in B-4. When 1