In ultrabasic-basic rocks, copper-nickel and pyrrhotite ores, cobalt is a constant companion of nickel. In this regard, the observed geochemical anomalies in moraine sediments above the above objects are characterized not only by elevated nickel and copper, but also by cobalt ...

Lithochemical survey in the conditions of the Kola Peninsula and Karelia is now beginning to be widely used in combination with geophysical methods at the stage of detailed prospecting. Drilling verification confirms the high efficiency of the method, which allows rejecting numerous geophysical anomalies caused by virtually nickel-free pyrrhotite ores and objects of non-metallic nature.

When searching for sulfide ores, sulfur is usually not determined in lithochemical samples. Meanwhile, at clark values in the lithosphere of 0.047%, its content in sulfide ores reaches tens of percent. Thus, in samples of sulfide copper-nickel ores of Allarechensky and Monchegorsk districts of the Kola Peninsula up to 27-33% of sulfur was found, in .samples of pyrrhotite ores of Allarechensky district 20-26%.

The search for sulfide copper-nickel ores on the Kola Peninsula and Karelia in the areas of continuous overlapping of bedrock by moraine sediments is very difficult. Geophysical methods, widely used in these conditions for prospecting purposes, often do not give an unambiguous answer about the causal relationship of the induced anomalies. The methodology of lithochemical survey developed by the Leningrad Mining Institute in relation to these conditions can provide significant assistance in improving the efficiency of prospecting. It is currently being implemented in a number of geophysical parties of the Kola District Geological Exploration Department and the Western Geophysical Trust in order to sort out geophysical anomalies. Application of lithochemical survey in one of such parties in 1966 in combination with geophysical methods led to the discovery of mineralization at a depth.

The formation of voids in rocks during the development of karst is usually explained by the dissolving action of water and mechanical destruction of rocks with the removal of particles by groundwater. The study of deep karst at the Leningrad oil shale deposit shows that the formation of voids in carbonate rocks can also go at metasomatic processes - as a result of secondary dolomitization of limestone.

The methodology of lithogeochemical survey in conditions of overlapping of bedrock by moraine formations of considerable thickness differs significantly from the methodology used in cover el in dealluvial deposits. This difference, as we found in one of the regions of the Kola Peninsula in the search for copper-nickel sulfide ores, is due to the greater importance of salt halos in scattering than mechanical ...

In the far north, under conditions of moraine deposits, plant litter serves as the source material for samples in biochemical surveying in connection with the search for copper‑nickel and polymetallic ores. After sampling on a predetermined grid (depending on the survey scale), the litter is dried, ashed, and its ash (usually by volume) is submitted for spectral analysis. Based on the results of the analysis, graphs of the content of copper, nickel, and other elements, or maps of isoconcentrations, are constructed. According to this scheme, biochemical surveying is currently carried out by production organizations.

A large number of deposits of ores of various metals and many non-metallic minerals are associated with carbonate rocks. According to I. I. Knyazev, more than half of the world's production of zinc and lead comes from deposits occurring in limestones and dolomites. Polymetallic deposits of the replacement type in limestones and skarn-type deposits are widespread in Transbaikalia, Central Asia, and other ore regions. According to V. S. Kormilitsyn, about 90% of polymetallic deposits in one of the regions of Eastern Transbaikalia, including all the larger objects, are confined to dolomites; about 8% of deposits are in limestones. Many deposits of iron, manganese, copper, silver, gold, mercury, and other metals are associated with carbonate rocks. In many ore regions of the Union, lead-zinc and other hydrothermal mineralization, as noted by F. I. Wolfson, is localized within structural levels enriched in carbonate sequences, while such mineralization is completely absent in deeper structural levels composed of various shales, quartzites, effusive rocks, and other rocks enriched in aluminosilicate components. Epigenetic mineralization forming among carbonate rocks is more often observed in dolomite horizons than in limestones. In this connection, the identification of dolomites acquires significant importance in geological mapping and prospecting.

As studies in the South Urals have shown, the determination of nickel, copper and zinc or the last two of these elements is of great importance in the metallometric survey for the search for copper and cobalt ores, spatially gravitating to ultramafic rocks or occurring among metamorphic shales or rocks of the greenstone belt of this province.

Pre-treatment of samples in the drop method as well as in other methods of chemical analysis depends on the elements to be determined and those compounds in the form of which they are found. In metallometric surveys for polymetals, loose material from the oxidation zone is usually received for analysis. In such cases, sample pretreatment can be carried out with one concentrated HCl. Samples containing sulphides are treated with concentrated HCl in the presence of an oxidizing agent. In the proposed variant of the method of analysis of zinc and lead from a single sample as an oxidizing agent is recommended Berthollet's salt.

The emergence of drop analysis as an independent analytical method dates back to 1920. This method, which allows working with a minimum expenditure of reagents and time, was first developed in the Soviet Union by N. A. Tananaev. Drop analysis is one of the methods of microchemical analysis. However, this method can achieve the accuracy inherent in colorimetry in general only in certain rare cases. When determining on a drop plate, colorimetric comparison is much more difficult. Particularly difficult is the analysis in small test tubes. The problem of determining small quantities of elements attracts the attention, as is known, of specialists in various fields of knowledge, including geologists. The proposed method of semi-quantitative determination of zinc based on the drop analysis method was developed by us at the end of 1952. It is aimed at obtaining more reliable indicators that provide a quantitative assessment of the element being studied.

"Mapping of limestones is the first stage of polymetallic exploration for deposits of the replacement type in limestones and skarn polymetallic ores of the Tetyukhin type. Geological mapping, as is known, does not encounter any particular difficulties in areas of good rock exposure. Where rocks are covered by modern deposits of even small thickness and vegetation is developed, geologists are forced to resort to mining. For mapping in closed areas, geophysical exploration methods are increasingly used, in particular, magnetic exploration, electrical exploration, T-survey and other methods. However, the use of these methods is often limited by the small difference in the physical properties of rocks. As a component of the complex in geophysical work for mapping limestones, the carbonate survey method is proposed. The carbonate survey method, as a quantitative method of rock analysis, can serve as a methodological basis for studying mechanical dispersion halos. Its use for this purpose will provide an opportunity to better understand the laws of dispersion and ore components.