Red Granite Research Articles

Transport of Magma in Granitic Mush Systems; an Example From the Götemar Pluton, Sweden

AbstractGranitic magma bodies form in the ephemeral part of magma mush systems and are emplaced by a variety of mechanisms in different tectonic settings. This study investigates how granitic magma emplacement processes and tectonomagmatic interactions assert control over the architecture of mush state pluton‐scale magma transport pathways. The 1.45 Ga shallow‐crustal Götemar pluton is a 4.5 km diameter circular pluton that consists of three granite units: a coarse‐grained red granite, a medium‐grained pale to red granite, and fine‐grained pale microgranite sheets. We employed geological mapping supported by Anisotropy of Magnetic Susceptibility (AMS) to examine the magmatic and regional tectonic controls on late‐stage magma transport in the Götemar granitic magma mush system. Multiple parallel arcuate subhorizontal microgranite and medium‐grained granite sheets (from 0.1 to 10s of meters thick) were mapped within the pluton. The arcuate sheets pinch out from the northern part of the pluton toward the SE inferring magma propagation direction. A dominant set of vertical granitic sheets within the granite body strikes NW‐SE. The AMS fabrics are contact‐parallel in the main medium‐grained granite body and indicate inflation. Within the microgranite sheets, the AMS fabrics are parallel to the sheet strike and support a sheet propagation direction to the SE. The Götemar pluton displays a clear link between arcuate (concentric) magma‐transporting sheets and concentric strain‐partitioning related to the intrusion of medium‐grained granite magma. The vertical magma sheet orientations are consistent with an NE‐SW extensional stress field that is associated with the extensional back‐arc stress regime of the contemporary Hallandian Orogen.

Cyclic Impact Test with the Hopkinson Bar: Application to Granite

A laboratory scale cyclic impact loading test was developed by modifying a Hopkinson Bar test setup. The modifications involve placing a special shank piece between the striker and the rest of the setup. The shank transmits the impact loading and enables the use of compressed air for rapid reloading of the striker. The short shank is in direct contact with the specimen, i.e., there is no long input bar. With this configuration residual wave motion and reloading of the specimen is avoided. Behind the striker an output bar and momentum trap bar are placed for specimen loading measurement and removal of the wave motion in the system, respectively. The trap bar is stopped by a pneumatic actuator, which also resets the bars and the specimen before the next impact loading. The compressed air flow driving the striker is controlled by high-speed electropneumatic valves connected to a control unit and operated in simple open-loop control. Numerical simulations of both the striker motion by compressed air and dynamic loading wave propagation during impact were used in the design phase as well as setting up the test parameters. The test setup is able to produce stable cyclic impact loading at a frequency of up to 10 impacts per second with striker velocity up to 9 m/s. The feasibility of the test method is demonstrated by providing data from cyclic Brazilian disc experiments on Balmoral Red granite at both impact and quasi-static cyclic loading.

Mineralogical constituents and radioactivity analysis of commercial granitic ornamental stones: Assessing suitability and radiation safety

Several commercial granitic rocks are widely used as decorative material (ornamental stones) due to their durability and fantastic colors. The present study aims to identify the mineralogical constituents as well as natural radioactivity of seven granitic rocks known as Gandonna, Pink Granite, Fantazia, Buff granites I, Buff granites II, Qusseir brown, red granites in order to deduce their suitability for different applications (decorative stone). Accordingly, in the petrographic investigation, the examined rocks comprise different proportions of essential minerals (potash feldspar, quartz, and albite) with some secondary minerals such as kaolinite and chlorite minerals.238U,226Ra,232Th and40K activity concentrations were detected by using NaI (Tl) scintillation γ-ray technique. Fantasia (av. 4.13 ± 5.85, 10.77 ± 1.9 Bqkg−1), and Gandonna (av. 12.4 ± 10.12, 35.01 ± 3.81 Bqkg−1) samples have the lowest mean238U, and232Th activities value, relative to other rock samples, which are lower than the recommended levels of UNSCEAR. Except for absorbed dose rate, numerous radiological indices such as outdoor and indoor annual effective dose, radium equivalent activity, external and internal indices, excess lifetime cancer risk and organs of effective dose are calculated for the examined stations to deduce the radiation effects on human organs. The obtained results reveal that the natural gamma radiation from these rocks is within acceptable limits.

Green multiple-criteria decision-making method of selection of diamond cutting tool for promoting cleaner production in the natural stone industry

Selection of a reasonable diamond cutting tool (DCT) is a crucial Multiple Criteria Decision-Making (MCDM) problem for promoting cleaner production for a natural stone company. It has severe uncertainties in the decision information, complex interdependences among the DM criteria and needs to balance stakeholders' opinions and adopt the non-complete compensation idea in the DM process. This paper establishes a specialized index system with changing the evaluation object from ontology of DCT to the ‘stone machining system’ within the boundary demarcated by LCA. Decision-Making Trial and Evaluation Laboratory (DEMATEL) method is applied to analyze the interdependence relationships existing in the index system and then the indicators' weights can be obtained by Analytic Network Process (ANP) method. In order to avoid complete compensation among indicators, Preference Ranking Organization Method for Enrichment Evaluations II (PROMETHEE II) method is used to prioritize the alternatives and identify the most reasonable DCT. The new developed MCDM algorithm is expressed based on interval-valued fuzzy set (IVFS) theory to handle the uncertain information in DM process. Integration of IVFS theory with MCDM method allows the decision-maker to use linguistic variables which correspond to interval-valued fuzzy numbers to describe their judgments and ensures all the stakeholders' preferences can be trade-off in the DM process. In the case application, the proposed method has been applied to select a suitable DCT to cut the Lotus red granite (G3768) for a stone processing company in China. As a result, the iron-based DCT (TJ-15) obtained the highest priority net flow (0.373) among five DCT alternatives and it was identified as the most reasonable DCT for the case company. The application study demonstrates the effectiveness and robustness of the developed method and indicates that pursuit of matching DCT with the characteristics of natural stone is more rational than blindly adopting more advanced and expensive DCT.

Minmose the Miller. A Ramessid Serving Statue Preparing Incense (Berlin ÄM 24179)مينموز الطحان. تمثال خَدَم لتحضير البخور من عصر الرعامسة (برلين ÄM 24179)

Publication of a fragment of a red granite statue belonging to the 19th Dynasty high priest of Onuris, Minmose, in the Ägyptisches Museum und Papyrussamlung in Berlin (ÄM 24179). The statue, which describes itself as a shabti, shows Minmose as a miller of grain, which may also be understood as incense. Preliminary translations and commentaries are offered for the statue’s texts; these are developed out of unpublished work by Jacques Jean Clère, records of which are held in the Griffith Institute, Oxford. Some implications of these inscriptions for interpreting the statue’s form and context are also discussed.

Comparison of DEM Models with Different Elemental Dimensions for TBM Disc Cutter Rock Fragmentation

Disc cutters are the dominant tool used in the excavation of hard rock formations in any underground construction application, such as when tunneling using tunnel-boring machines (TBM), as well as in shaft- and raise boring operations. Optimization of the cutting geometry of a given disc cutter for application in a rock formation often involves full-scale cutting tests, which is a difficult and costly proposition. An alternative to full-scale testing is the numerical simulation of TBM disc cutters for optimization under different settings. Recent efforts in the field of numerical simulations of rock cutting have shown the relative success of discrete element models, such as particle flow code (PFC), to simulate two- and three-dimensional rock fragmentation. This study is focused on a sensitivity analysis of PFC simulation of rock-cutting relative to the size of the elements. The calculated cutting forces were compared with the recorded forces under various conditions during full-scale tests using a linear cutting machine (LCM) on Colorado red granite (CRG). The estimated cutting coefficient and specific energy in the LCM tests and simulations showed good correlations, which validates the numerical simulation results. Two- and three-dimensional models showed that two-dimensional numerical models can offer a qualitative assessment of crack development, whereas three-dimensional models could be used to estimate the specific energy when cutting. The results can help in predicting the cutting forces in different rocks and ultimately improving disc-cutter geometry and cutter-head design.

Comparison of the structural behaviour of monolithic and masonry obelisks: Obelisk of Theodosius and Walled Obelisk in Istanbul

In this paper, the structural behaviour of the Obelisk of Theodosius and Walled Obelisk, located near the Sultan Ahmed Mosque in Istanbul, is investigated. The Obelisk of Theodosius is made of an integrated and solid red granite that stands on four pieces of bronze cubes and large pieces of stone cubes. The Walled Obelisk is made of small pieces of limestone that stand on only one large piece of stone cube, without bronze cubes. The purpose of this study is the comparison of the structural behaviour of these two obelisks and the effect of their supporting base on their performance under seismic loading. The nonlinear three-dimensional finite element method is used for modelling and the Willam-Warnke failure criterion is adopted for investigation of brittle fracture mechanism. The results of analysis show that the Walled Obelisk is more flexible than the Obelisk of Theodosius. However, the existence of four bronze cubes and four red granite cubes at the corners of the supporting base increases the flexibility of the Obelisk of Theodosius.

Geochemical and geochronological constraints on the Mesoproterozoic Red Granite Suite, Kunene AMCG Complex of Angola and Namibia

Anorthosite-mangerite-charnockite-granite (AMCG) suites form large batholiths emplaced during the Proterozoic Eon. Magma source(s), emplacement mechanisms, and the tectonic setting of AMCG suites remain poorly understood. We present new major and trace element geochemistry combined with U-Pb zircon geochronology and Lu-Hf isotopes for the Red Granite Suite, part of the Mesoproterozoic Kunene AMCG Complex (Angola and Namibia), and its Paleoproterozoic host rocks, to elucidate the petrogenesis and tectonic setting of the Kunene Complex granitoids. The studied samples are mostly granite with minor syenite and quartz monzonite. LA-MC-ICPMS U-Pb zircon dates indicate that felsic magmatism was active for at least 90 Myr (1450–1360 Ma) and shows spatial and temporal similarities with emplacement of the main anorthositic body. The geochemistry of the granitoids did not change substantially over time, with predominant alkali-calcic, A-type granites. The εHf(t) of zircon grains in the Red Granite Suite ranges between −11.3 and + 1.6. These results, when considered together with Hf isotopic compositions of zircon from the Paleoproterozoic host rocks (εHf(t) = -11.3 to + 0.4) and xenocrysts in the Red Granite, suggest the suite is derived from the mixing of a Paleoproterozoic crustal component with juvenile mantle-derived material. Syn-magmatic east–west shortening has been documented in both the anorthosites and Red Granites at the southwestern margin of the Kunene Complex in the period 1400–1380 Ma. The results from the Hf isotopes on zircon, combined with the long-lived nature of magmatism, the syn-contractional magmatism, at least locally, and the requirement for extensive crustal melting, suggest that the Red Granite Suite was formed in a convergent margin setting. This challenges the traditional view that A-type granitoids are restricted to anorogenic, extensional settings, and is in agreement with recent views on the petrogenesis of massif-type anorthosites and their associated MCG magmatism.

Radon and thoron concentrations in the southwest region of Angola: dose assessment and implications for risk mapping.

Indoor radon (222Rn) and thoron (220Rn) are the most important natural sources of ionizing radiation to the public. Radiological studies that assess simultaneously 222Rn and 220Rn, and their controlling factors are particularly scarce in African countries. Hence, we conducted a survey of indoor 222Rn and 220Rn in buildings located in the SW region of Angola. Bedrock samples were also collected, and a borehole was executed to assess 226Ra and 224Ra activity concentration, 222Rn and 220Rn exhalation and emanation potential in the surface and at depth. The aim of this study was to determine the factors (geological and anthropogenic) that may influence the annual inhalation dose (AID) received by the population. Overall, the sum of indoor radon and indoor thoron concentrations, labelled the total indoor radon concentration (TIRC), was higher than 300Bq/m3 in only 5% of the buildings studied. The contribution of 220Rn to the TIRC averaged 35% but may reach 95%, demonstrating the relevance of discriminating radon and thoron in indoor radon surveys. Indoor 222Rn and 220Rn were not correlated, indicating both must be estimated to properly assess the AID. Indoor 220Rn concentrations were statistically different according to the building materials and type of usage. Higher 222Rn and 220Rn concentrations were observed in dwellings compared to workplaces. The median AID estimated for dwellings was 1.50mSv/y compared to 0.26mSv/y for workplaces, which are lower than the estimated average radiation exposure due to natural sources of 2.4mSv/y. AID values higher than 1mSv/y effective dose threshold established in the Council Directive 2013/59/EURATOM for the purpose of radiation protection in workplaces were observed in 12% of the workplaces studied suggesting the need for mitigation measures in those buildings. The analysis of bedrock samples revealed statistically significant correlations between 224 and 226Ra activity concentration, and 220Rn and 222Rn exhalation and emanation potential. The borehole samples indicated a strong influence of weathering processes in the distribution of radioisotopes. The highest 226Ra and 224Ra activity concentration, and 222Rn and 220Rn exhaled per unit mass, TIRC and AID were observed in association with A-type red granites and porphyries. We conclude that both geological and anthropic factors, such as the type of building usage and building materials, must be considered in dose assessment studies and for the development of risk maps.

ДО БІОГРАФІЇ РОДИНИ ВОЛИНСЬКИХ ЧЕХІВ-КАМЕНОТЕСІВ ДЛОУГІ

The article presents biographical facts from the life of family members of the Volyn Czech stonemasons Dlougi. The first known mention of Vaclav Yosypovich Dlouga’s activity belongs to Oleksiy Abramov, the author of the book «Lenin’s Mausoleum», the first edition of which was published in 1963. It contains the stonecutter’s recollections of the search for black labradorite in the Golovinsky quarry in the Zhytomyr region for the Mausoleum. The results of the study of Zhytomyr cemeteries for the presence of graves of members of the Dlougi family, as well as for the presence of monuments made in the Dlougi workshop are described. Tombstones made in Dlouga’s workshop have been preserved in the historical cemeteries of Zhytomyr, in particular in Poland, Vilsk (Russia), Smolyan, and Pylypon. The metric records of members of the Dlougi family are analyzed, and the transformation of the Czech surname in the records of that period is traced. Data on the main achievements of masters on outstanding constructions are given, technological features of processing of a stone which were advanced at that time are described. Dloughy’s stone-cutting workshop made monuments from labradorite, gray and red granite, plinths, stairs and iron fences. At the same time, data on the birth, professional and social activities of members of this family are generalized. The results of research of cemeteries in Zhytomyr, where there are graves of family members, as well as monuments made in Dlougi’s workshops are presented. The facts of political repressions on the basis of ethnicity of family members are described. In the late 1920s and early 1930s, the Czech population of the Zhytomyr region fully experienced the punitive policies of the Soviet government, suffering significant losses during «linear» arrests on national grounds. Family ties of Czechs with the surname Dlougi, who lived on the territory of Volyn Gubernia at that time, have been established. The contribution of the Czech family to the technology of stone processing, the ability to be enterprising and socially active is emphasized.

Experimental investigation of rotary ultrasonic face milling on red granite: A comparison with conventional grinding

Long-term sustainability with cost-effective machining and materials are used in many companies these days. Also, precise machining on brittle and hard materials is becoming a challenge for production engineering. Rotary ultrasonic face milling (RUFM) is an unconventional milling process that is preferred to perform precise surface machining on such materials. The research work aims to analyse the enhancement in conventional diamond grinding (CG) due to the addition of ultrasonic vibration and compare both processes (RUFM and CG). Analysis of variance (ANOVA) technology was applied for the analysis. The scanning electron microscopy (SEM) technique was used to analyse the tool wear after milling operation. The controlling factors used for the study were feed rate, depth of cut, and ultrasonic power. The outcomes of the study showed an increment in material removal rate during RUFM compared to CG. Material removal rate (MRR) also increases with increment in each level of controlling factors. Surface roughness (SR) increases with the addition of ultrasonic vibration during RUFM. Also, SEM technology shows the complete removal of diamond grits at the bottom surface of the tool. The research concluded that tool life and material removal rate get improved but the reduction in surface finish during RUFM while comparing to CG.

Crystal transfer from magma to wallrock during syntectonic granite emplacement

Field, microstructural and mineral compositional evidence from the Mesoproterozoic K-feldspar megacrystic Red Granite at Oncócua Platform (southwestern Angola) is consistent with crystal transfer from magma to wallrock during syntectonic intrusion. K-feldspar megacrystic Red Granite intruded during folding of wallrock tonalite. Enclaves of the wallrock tonalite are elongated parallel to Red Granite intrusive contacts, a K-feldspar megacryst and hornblende-defined magmatic foliation, and a gneissosity in the Red Granite. Stromatic layering present in the tonalite is crosscut by the Red Granite intrusive contacts or is isoclinally folded with fold axial planes and hinges filled with Red Granite. K-feldspar megacryst clusters and curved grain boundaries (i.e. contact melting), as well as thin Red Granite fold axial planar sheets containing K-feldspar megacrysts that are typically wider than the sheets themselves, are all consistent with melt loss and crystal accumulation during solidification. The wallrock tonalite also hosts K-feldspar megacrysts and hornblende phenocrysts that are interpreted to be the same population as those in Red Granite, on the basis of their size, shape, nature of inclusions, compositions and compositional zoning. We propose that these crystals were transferred from the intrusive Red Granite magma to the wallrock tonalite via magmatic conduits that subsequently collapsed due to external stresses, leaving behind the larger crystals. The pristine preservation of intrusive relations at Oncócua Platform may mean that crystal transfer from magma to wallrock is more common in incrementally assembled granitoid plutons than previously thought. Supplementary material: Mineral chemical data are available at https://doi.org/10.6084/m9.figshare.c.5448664

Experimental Investigation of Rotary Ultrasonic Face Milling on Float glass and Red granite

Experimental Investigation of Rotary Ultrasonic Face Milling on Float glass and Red granite

EXPERIMENTAL STUDY ON COMPRESSIVE STRENGTH AND FLEXURAL RIGIDITY OF EPOXY GRANITE COMPOSITE MATERIAL

In Egypt, large quantities of coarse granite wastes are produced annually during the quarrying operations of granite rocks. This waste represents a potentially useful source of material for a variety of applications such as a filler material in epoxy granite composite material. In this work a new eco-friendly composite material studied as a substitute for machine tools traditional materials, like cast iron, to produce better efficiency with lower cost. This study aims to investigate the mechanical properties of granite epoxy composite by using the local epoxy (kemapoxy 150) and the granite residues in the Egyptian quarries. The investigated processing variable was epoxy content, and the mechanical characterization ware carried out by compressive and flexural tests according to the ASTM standard method B. Commercially available, Aswan red granite was procured, crushed, and sieved to three size ranges from 0.150 to 8 mm, respectively. Epoxy ratios of 80:20, 85:15 have been used with granite aggregate size mix with small, medium, and coarse size proportions of 50:25:25 respectively for preparing the specimens with granite granular size range (0.150-8) mm. The results show that Epoxy granite composite with granite to epoxy ratio of 80:20% wt. induced the highest compressive strength (72.15 MPa) while the composite with the ratio of 85:15% wt. induced the highest flexural strength (20.1 MPa). Epoxy granite composite show superior results with respect to cement concrete, polyester concrete, and natural granite.

Geology of the Souter Head subvolcanic complex, Aberdeenshire, Scotland: an Ordovician granite-related Mo–(Bi–As–Au) system

ABSTRACTAn Ordovician subvolcanic intrusive complex hosted by Neoproterozoic metasediments crops out at Souter Head about 6km S of Aberdeen, Scotland. The complex is composed mainly of two-mica red granite and breccia with minor dykes of pegmatite, quartz porphyry, felsite and dolerite, and widespread quartz veining, hydrothermal alteration and minor molybdenite mineralisation. Anomalous levels of bismuth (Bi), arsenic (As) and gold (Au) occur in quartz–pyrite veins. The complex has been mapped and the major- and minor-element geochemistry, including rare-earth elements of intrusives and mineralisation, has been determined. These data reveal a complex tectonic, intrusive and hydrothermal history. The intrusives are peraluminous and magnetite-, muscovite- and garnet-bearing. The youngest member, a quartz porphyry, is highly fractionated. There are two stages of hydrothermal activity: the first is linked to the explosive release of volatiles from a granite cupola and breccia formation; and the second, widespread quartz veining. Mo is associated with both stages, and Bi–As–Au anomalies are found in late quartz–pyrite veins. The mineralisation is classified as a granite-related vein-type Mo system. The unique preservation, in the Grampian terrane, of an Ordovician subvolcanic complex may be attributed to pre-Devonian movements on the nearby Dee fault and possibly also the collapse of the magma chamber following the explosive release of volatiles. The combination of large size, poor exposure and abundant multi-stage hydrothermal activity suggests that there is potential for further Mo and possibly Au mineralisation in this complex. Further mineralisation of this style may be present in the NE Grampian terrane.

Assessment of magmatic versus post-magmatic processes in the Mueilha rare-metal granite, Eastern Desert of Egypt, Arabian-Nubian Shield

The Mueilha rare-metal granite, exposed in the central Eastern Desert of Egypt, is a post-collisional intrusion that formed in the final magmatic stage of the evolution of the Arabian-Nubian Shield. The Mueilha intrusion was emplaced as a high-level magmatic cupola into metamorphic country rocks. It consists of two cogenetic intrusive bodies: an early phase emplaced at shallow depth and now penetratively altered to white albite granite and a later phase of red granites emplaced at greater depth that better preserve magmatic features. The albite granite is less common and represents the upper margin of the Mueilha intrusion, the apex of the magmatic cupola. The red granites are volumetrically dominant and appears to have crystallized from the margins inward, forming a composite pluton zoned from muscovite granite to alkali feldspar granite. All parts of the Mueilha pluton appear to have been emplaced within a short time interval, before complete crystallization of the earliest phase. The geochemistry of the Mueilha granites is typical of rare-metal granites, characterized by high SiO2, Na2O + K2O, Nb, Rb, Ta, Y, U, Th, Sn, and W with depletion in P, Mg, Ti, Sr and Ba. They are weakly peraluminous and highly fractionated with A-type character. The chondrite-normalized REE patterns have strongly negative Eu anomalies, typical of highly differentiated granites that evolved through a transitional magmatic–hydrothermal stage. The primary magma feeding the Mueilha intrusion was generated by partial melting of the juvenile crust of the Arabian-Nubian Shield; it subsequently underwent extensive fractional crystallization and metasomatism by late- to post-magmatic fluids. Separation of fluids from the oversaturated melt promoted both diffuse greisenization and focused segregation of pegmatite and fluorite and quartz veins. Alkalis liberated from feldspars consumed by greisenization were redeposited during albitization in the uppermost part of the magma chamber. Despite penetration of the intrusion boundary by discrete dikes, veins, and aphophyses, diffuse alteration of the metamorphic country rocks is not apparent. Primary columbite-series minerals crystallized from the melt and were later partly replaced by secondary Nb and Ta minerals (fluorcalciomicrolite and wodginite) during hydrothermal alteration.

Comparative evaluation of the bitumen binders adhesion by the methods normalized by national standards of Ukraine

Problem. Bitumen binders as a component of the asphalt pavement must be characterized by a certain list of qualities. It includes high cohesion values, good adhesion to the surface of all mineral materials, low temperature susceptibility and high stability of properties during technological proceeding and durability pavement period. The high rate of a new adhesives and adhesion assessment methods invention points on the topicality of the problem of improving binder adhesion and it’s validate assessment both in Ukraine, and abroad. Goal. There are a few national standards (GOST 11508-74, DSTU B V.2.7-81-98, DSTU 8787:2018, DSTU EN 12697-11:2018) that regulate the adhesion assessment of bitumen in Ukraine. The comparative analysis of adhesion values, founded by these methods, is a purpose of this research work. Methodology. Three mineral materials (quartzite, grey and red granite) of different grading are chosen for the tests. Bitumen modified by polymer, warm mix additive and a surfactant additive are used to evaluate the susceptibility of the test methods to the presence of these additives in bitumen due to the purpose of this research work. Results. The advantages and disadvantages of the analyzed methods are set due to the results of this research. It is found that difference in temperature ranks and mineral grading, set by test conditions, leads to the significant difference in adhesion values. Originality. The comparative analysis of test methods that regulates bitumen adhesion quality in Ukraine, and finding their advantages and disadvantages make the scientific originality of the presented research. Practical value. Due the research results, the advantage of adhesion value quantitative evaluation and its validity is set as a feature of adhesion test by the DSTU B V.2.7-98 method in comparison with other test methods. The improvement of the DSTU B V.2.7-98 method enables it to the modified bitumen adhesion assessment and makes the test results compatible with the European Rolling Bottle Test (DSTU EN 12697-11:2018) results.

Analysis of change in the decorative properties of granites under thermal exposure

We investigated samples extracted in Ukraine from nine granite deposits experimentally. We performed tests of granite samples at high temperatures of 200, 400, 600, and 900 °C. All presented granites showed a change in the color of surface at a temperature of 200 °C and higher. The behavior of granites under heating depends on their mineral composition, structure and texture. Surfaces of all samples became lighter and some granite samples lost saturation of their color. The largest increase in L component (image of stone samples brightens) of the CIELab color system occurred on Cardinal Gray and Carpazi granite samples of natural stone under heating to 900 °C. The increase made up 42 and 44 %, respectively. The smallest increase in L component was on Gray Ukraine and L granites under heating to 900 °C. It made up 4 and 8.5 %, respectively. The effect of temperature was less visible on red granite, since both fresh and heated samples had a similar red color. Flower of Ukraine granite samples acquired a uniform violet-pink color at the temperature of 900 °C due to the content of apatite and fluorite. Red spots appeared on gray granites under heating. The red spots located mainly around mica and other minerals, which were rich in Fe. Reddish-brown spots appeared at the temperature of 200 °C on green Verde Oliva granite. Red spots occupied 67 % of the sample area under heating to 900 °C. We observed the greatest color change on granites, where the phase transition of dark-colored minerals (biotite and pyroxene) into polymorphic minerals took place. This gave granite samples a light color, as the minerals changed color from black to gray or white. Quartz provided the shades of white. White microcracks appeared under heating of quartz. Noticeable aesthetic damage appears at temperatures from 200 to 400 °C at the surfaces of natural stone samples. Thus, one can consider a fire with temperatures lower than this threshold as a “safe” fire in terms of aesthetic damage, if we take into consideration the heating coefficient of fire only and exclude ash and gases.

Small scale testing of PCD and WC-Co tooling in rock cutting using longitudinal turning

Rock cutting and crushing stands for a considerable part of the world use of Cemented Carbide (CC). CC is preferred due to its hardness while maintaining high fracture toughness. However, new cutting tool materials are developed allowing increased efficiency whilst minimizing the use of critical raw material such as tungsten and cobalt. One material showing promising capabilities is Polycrystalline Diamond (PCD).Field testing of new wear resistant tool materials are known to be notoriously difficult due to issues controlling the test environment. To further support the development of new and more wear resistant tool materials there is a need for an improved methodology of laboratory testing of rock cutting.In this work a test rig was developed and testing methodology was validated, when using cutting tool inserts with standard shapes, such as round double sided general purpose insert RNGN and dome shaped buttons while machining and crushing bars of red granite by longitudinal turning using a standard lathe. Optical microscopy, 3D data of Volume Difference Measurements and SEM were used for analyzing tool wear. Different grades of CC showed similar wear mechanisms irrespectively of tool geometry. The PCD grade did not show similar wear mechanisms, but did outperform CC grade in regard to wear resistance.

Application of Coded Excitation Signals for Measurement of Rock Ultrasonic Wave Velocity

The accurate measurement of ultrasonic velocity requires the detected waveforms to have a high signal-to-noise ratio (SNR). Coded excitation technique (CET) can improve the SNR without resolution loss. This study introduces the basic principles of phase-coded technology and gives a synthetic and experimental evaluation of Barker and Golay codes. All the results show that CET can increase the SNR, but the gain in SNR (GSNR) is lower than the theoretical value. The velocity measurements on red sandstone and granite verify that the Barker code has better pulse compression performance than the Golay code. Besides, the application of Barker-coded signals on the velocity monitoring of uniaxially compressed rock proves that the Barker CET is reliable.