Mineral inclusions in the granulated quartz of deposits Southern Ural

Igumentseva m.A.

Institute of mineralogy UrB ras; South-Ural State University, Miass, Russia

maria@mineralogy.ru

Nowadays, great interest is being shown in what is known as special pure quartz, widely used in high-tech industries. The Kuznechihinsky deposit and Berkutinsky fault are the concerned facilities where the special pure quartz can be established and extracted. To begin with, purity level of the quartz is determined by the presence of inclusions and impurity. Of particular interest are the mineral inclusions, present as impurity in quartz concentrates and forming multicolored streaks in glass build-ups.

In this work, quartz-fault formations of Kuznechihinsk (fault № 191, 413 and 414) and Kyshtymsk (Berkutinsk fault) deposits are studied. The basic part of quartz of all the faults of the Kuznechihinsk deposit consists of gray fine-grained «ice-like» quartz, related to the «egustinsk» type. Quartz is characterized by the presence of dense network of fissures or cracks. At the Berkutinsk fault, two types of quartz are found: white fine-grained quartz (type I) and grey fine-grained semitransparent quartz (type II). Quartz of both the types are related to the «ufaleisk» type. Quartz of the I type forms the main part of the fault and is found in its central part, whereas, quartz II is found in the places where fault is in contact with the host rock.

Quartz studies, using the impulse cathode luminescence method showed that in the quartz spectra besides the main band of 490 nm, due to the aluminum ions, isomorphically replacing atoms of silicon, band connected by the ions of Mn²⁺ and Fe²⁺ in the mineral inclusions are present. It is established that the band intensity of 490 nm changes a great deal and depends upon the content of aluminum as well as conditions of quartz formation .

It is proved through the quantitative mineralogical analysis and optical microscopy method, that the main mineral inclusions in the quartz are mica (phengite, biotite), fieldspars (microcline, albite), garnets (Ca-Mg-almandine, andradite), and apatite. The lowest content of mineral inclusions are found in grey fine grained quartz belonging to the Kuznechihinsk deposit. The highest quantity of the mineral inclusions, especially in elctromagnetic and heavy residue, is found in the grey fine-grained quartz of the Berkutinsk fault.

According to the data of the energy-dispersive analysis, it is 3.33 ф.е representsestablished that the phengite with the content Si⁴⁺ = 3.14 mica. Fieldspar are represented by well-disposed albite and potsh fieldspar or microcline which corresponds to the infrared spectroscopy data. According to the Moessbauer spectroscopy data, phengites are highly oxidized (Fe³⁺/ ΣFe ≥ 66 %), oxidation level of the iron ions in the biotites changes a great deal from 19 to 65 %. It is proved that ions of bivalent iron is found in cis- as well as trans- positions, whereas ions of trivalent iron hold the cis- positions.

According to the data of SPT mass spectrometry and optical emission of the concentration of the main structural impurities in the quartz of deep concentration in the Kuznechihinsky deposit is closer to the value characterized by the quartz of the IOTA standard of the firm Unimin. At the same time, content of the impurity in the quartz of the Berkutinsk fault exceeds the admissible value with respect to the following elements: Al, Na, K, Ca, Fe, Ti. Excess data are related to the presence of huge quantity of mineral inclusions in the quartz.

The work was conducted with the support of presidium programme RAS № 23, and in accordance with the State contract to perform research work for the state requirement № П-735 dated 20.05.2010, Programme Presidium № 23.