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The article provides an overview of experimental studies of charoite and charoite-containing rock formation hypotheses. The authors conducted experiments to clarify charoite and host rocks interaction and study charoite transformation processes at high temperatures. A series of experiments was aimed at improving the substandard charoite samples. The experiments show the formation of polymineral reaction zones due to the contact interaction between charoite and microcline-arfvedsonite lamprophyre. By studying the newly formed phases, the authors reveal the distribution of elements by phases and establish their compositions. It is shown that thermal decomposition of charoite leads to the formation of wollastonite, which amount increases with the temperature increase from 800 to 1000 °C, and heating above 1200 °C leads to the formation of pseudowollastonite. The physicochemical simulation of charoite decomposition under the specified temperatures and pressure shows the following paragenesis: quartz, wollastonite, alkaline pyroxene (aegerine), microcline, rhodonite, and sphene.The experiments prove the formation of charoite at low temperatures and the lack of silicate melt in the systems studied. The calculated values are consistent with the results of experiments conducted to study the charoite and host rocks interaction, which allows identifying phases potentially co-existing with wollastonite.Special studies using by the coloring technique were conducted to improve the decorative properties of charoite. The color close to natural high-grade charoite coloration was achieved by keeping the rock samples in the active bright purple dye 4KT solution for 72 hours at a temperature of 70 to 90 °C.

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The study of engineering and geological properties of anthropogenic deposits, widespread in the city of Samara. Their main properties have been identifi ed and a classifi cation based on the genetic principle has been developed. The results of a petrographic study of samples from cultural layers taken at an archaeological site are presented. Archaeological excavations were carried out on the territory of Khlebnaya Square, located in the oldest part of the city, in 2019. The object represents the cultural layers that were formed in the XVIII-XIX centuries at the site of the alleged location of the second Samara fortress. Petrographic studies of the samples were carried out under a binocular microscope at 8.75 times magnifi cation, in transmitt ed light of a polarizing microscope at 72 times magnifi cation and under a digital microscope (USB DIGITAL) at 10 times magnifi cation. It has been determined that the pebble fraction is represented by quartz ite and jasper fl int, the sandy and silty fractions are angular quartz fragments with an admixture of undecomposed organic remains. The organic cultural layers, which reach 7-8 m and more in the ancient part of the city, are especially powerful. Their presence is a limiting factor in modern urban construction.