ENIGMATIC STONE SPHEROIDS FROM SCYTHIAN BURIAL AT KRASNYI PODOL OF UKRAINE: PETROGRAPHIC CHARACTERISTIC, PLACE OF MINING AND PROCESSING METHODS

The results of a petrographic investigation of 80 stone spheroids from a Scythian burial near the village of Krasnyi Podol are presented. The results indicate that all the stone spheroids were made from the same type of metamorphic rocks, namely actinolitites. The petrographic characteristics of the actinolitites indicate that the initial raw material was obtained from a single deposit. The Middle-Dnieper Region of the Ukrainian Precambrian Shield is considered as the probable place for their mining. The authors do not exclude that the natural outcrops of actinolitites could initially have had spherical jointing due to the processes of physical weathering. This jointing provided an opportunity to obtain roughly spherical blanks directly at the mining site. But most of the studied stone spheroids have got their spherical shape by artificial firing. The latter manifests itself in the surface desquamation and oxidation of the outer parts of the stone blanks. At least some of the stone blanks were ground to varying degrees after the firing. Stone abrasive materials were used for this purpose. The listed facts allow us to postulate that stone spheroids found in the Krasnyi Podol burial illustrate the successive stages of their processing. The owner of the stone spheroids likely possessed special knowledge regarding their mining, production and use.

Evaluation of Microtexture Changes of Coarse Aggregate during Simulated Polishing

This paper presents application of optical microscope for evaluation of microtexture changes of coarse aggregate during simulated polishing in laboratory. Observations of the apparent changes on surfaces of seven different aggregates are presented. Simulation polishing of aggregate was performed in accordance with PN-EN 1097-8:2009. Images of the aggregate surface were taken with the optical microscope in the reflection mode in particular stages of polishing. Digital images were analyzed. Standard deviation was determined on the basis of the histogram of intensities from digital images of the surfaces of aggregate grains which was assumed as the measure of changes in microtexture during simulated polishing (namely the σn parameter). Statistical analysis has shown that the changes of the σn parameter between the particular stages of polishing confirm certain trends related to the petrographic characteristic of the rocks. Aggregates which included minerals of similar hardness (granodiorite, dolomile, basall) were more prone to polishing than gabbro and postglacial. Regeneration of the microtexture, the recovery to its original asperity, occurred in the case of quartz sandstone and steelmaking slag.