Interest in Iceland spar, a transparent variety of calcite, stems from its extensive use in optical devices. Particular attention is attracted to Iceland spar from the point of view of studying the causes that cause coloration of crystals, and identifying ways of directing the impact on its intensity ...
Carbonatometric method is based on the study of calcite scattering halos - primary and secondary, which are the most important direct search signs of deposits of this mineral. When searching for deposits of Iceland spar by existing methods (geological survey, clastic-river) they are used only partially. Researchers pay attention only to coarse clastic mechanical (secondary) scattering halos, as well as to the presence of veins or calcite phenocrysts in the bedrock, which are primary (macro) scattering halos. ...
The most important task of the present time is the protection of nature and the most effective use of natural riches, in particular deposits of monocrystalline raw materials: Iceland spar, rock crystal, optical fluorite, tourmaline, muscovite, phlogopite, precious and ornamental stones, etc. Deposits of these minerals are quite rare, and accumulations of high-quality single crystals in in substantial quantities are encountered even more rarely. ...
Iceland spar, which is a transparent variety of calcite, is characterized by a number of important properties that determine the areas of its use in science and technology, as well as the features of the study of deposits, their industrial development and processing of crystals...
The largest deposits of Iceland spar are confined to lava beds of basic composition (the first type of deposits), to small dolerite intrusions (the second type of deposits), and to zones of tectonic crushing in tuffogenic rocks (the third type of deposits). By now, the known deposits have been relatively well studied and the main geologic regularities of their spatial distribution have been revealed.
The multifaceted and fruitful pedagogical and scientific activity of Vadim D. Nikitin, Professor of the Department of Mineralogy, Doctor of Geological and Mineralogical Sciences, is closely connected with the Leningrad Mining Institute, where he became a major scientist, a great connoisseur of minerals, a brilliant researcher of pegmatites.
Iceland spar is the main material of various kinds of optical parts, which are cut from. defect-free parts of natural crystals. The quality of crystals is determined after cutting them into plates by applying mechanical grinding and polishing of the cutting planes. Since most of the crystals contain one or another defect, most of the work on mechanical processing of plates is wasted. In addition, sawing crystals and their parts blindly (in most cases, the surface quality of crystals does not allow even tentatively identify defect-free areas) leads to the loss of valuable material.
В последние годы для получения поляризованного света широко применяются дихроичные поляроиды. Достоинствами их является сравнительная дешевизна, малая толщина, большая линейная и угловая апертура. Основными же недостатками можно считать следующие. Пропускание селективно по спектру, в результате чего значительно искажается спектральное распределение энергии в исследуемом световом потоке ...
In the basis of geological and industrial classification of deposits are based on the following main indicators: the shape and size of mica-bearing bodies, the conditions of their occurrence, the host rocks, the degree of saturation of the host rocks mica veins, the scale of deposits, -content and quality of mica, the complexity of deposits, the industrial importance of deposits, features of their genesis.These are the determining indicators for the choice of exploration techniques, industrial evaluation of the deposit and its development. We distinguish only four geological and industrial types ...
При исследовании кристаллов исландского шпата Нижне-Тунгусских месторождений было просмотрено более 15 000 кусков, выколотых по спайности, из которых часть была совершенно бесцветна, а большинство окрашено в желтый цвет различной интенсивности. По интенсивности окраски все кристаллы были разделены на пятнадцать классов: нулевой, I—XIV.
The study of inclusions in minerals is of great theoretical and practical importance. It allows us to more fully decipher the genesis of minerals, and consequently, to more correctly carry out an industrial assessment of their deposits. The study of inclusions in minerals that are raw materials for the optical industry, and, in particular, in Iceland spar, is especially important, since it reveals the nature of the main defects that prevent the use of crystals of these minerals for practical purposes. Iceland spar contains widespread solid, liquid and gas-liquid inclusions. This article highlights the results of the study of solid inclusions. The study of solid inclusions allows us to clarify a number of essential issues of the genesis of Iceland spar, as well as to explain the nature of defects in the optical material.
A set of magmatic formations associated with the Upper Paleozoic-Lower Mesozoic magmatic cycle, similar in geologic position, as well as in mineralogical and chemical composition, researchers refer to the Siberian Trappe Formation. This formation includes intrusive and effusive rocks of basic composition, pyroclastic formations of tuffogenic strata of the Angarsk series (Tunguska Formation), which were formed due to products of early phases of volcanic activity. These rocks within the northern and central parts of the Siberian Platform occupy a vast territory. For example, tuffogenic deposits of the late Paleozoic and early Mesozoic, as well as lava covers overlying them, are located in the basins of the Nizhnaya and Podkamennaya Tungusok, Kureika, Khatanga, upper and middle reaches of the Kotuy, Kheta and upper Olenek rivers. The area occupied by them is at least 700,000 km2. At present, magmatic formations of this territory attract great attention of researchers in connection with the development of such important issues as stratigraphy and tectonics of volcanogenic formations and processes of volcanism. The study of these issues will help to reveal the industrial prospects of this vast territory.
Iceland spar crystals have cleavage, low hardness, brittleness and high surface tension, therefore they are extremely sensitive to various types of physical impacts (impact, pressure, sudden temperature changes, etc.). Consequently, incorrectly applied exploration and mining techniques for this mineral can lead to the damage of a significant amount of optical material. In both domestic and foreign literature, these issues are not covered at all. There are only indications of the need for careful handling of Iceland spar crystals to avoid their damage, as well as wishes to develop deposits using open-pit rather than underground methods.
Many researchers have attempted to classify the pegmatite formations of Northern Karelia, but all proposed schemes suffer from a one-sided approach to taking into account the existing geological factors and use only one or two guiding ones, ignoring the rest. Thus, some divide all the pegmatites of the region into mica-bearing and ceramic [1], others classify them by mineral composition [3], others only by shape, and others by shape and the nature of the distribution of mica in the veins. None of the proposed classifications take into account the geological and structural factors characterizing the conditions of formation of industrial pegmatites. For these reasons, the listed classifications of industrial pegmatites of Northern Karelia are almost never used in prospecting and exploration work, as well as in assessing these deposits. The most perfect classification of pegmatites of Northern Karelia should be considered the classification proposed by V.D. Nikitin and P.P. Borovikov, in the compilation of which the author's materials were used. Studies of pegmatites in Northern Karelia conducted in recent years have provided a significant amount of material for determining the conditions of formation of pegmatites and classifying them according to genetic characteristics.
