Beryl Research Articles

Thermoluminescence characteristics of unannealed and a high temperature annealed green beryl

The thermoluminescence characteristics of natural green beryl are reported. Aliquots of the sample used were irradiated using a beta source at a dose rate of 0.1 Gy/s. The glow curves measured at 1 °C/s from aliqouts irradiated to a dose of 1 Gy have peaks at 74, 166, 280 and 422 °C. Only the peak temperature value of the peak at 166 °C is dose dependent, changing from 158 °C for aliquot irradiated to a dose of 0.1 Gy to 190 °C for aliquot irradiated to a dose of 100 Gy. Tm-Tstop and GCD analyses revealed that the peak which appears at 166 °C consists of two overlapping components near 165 and 187 °C. All the peaks are affected by thermal quenching to varying degrees. Activation energy values of the glow peaks calculated using GCD and E-Tstop analyses are in good agreement. Exposure of pre-irradiated beryl to light bleaches luminescence stored in it by the irradiation. TL emission in natural beryl may be dependent on previous thermal history in the environment.

New insights into chemical and spectroscopic characterization of beryl mineralization related to leucogranites in the west Wadi El Gemal area, southern Eastern Desert of Egypt

Our combined mineral chemistry and spectroscopic studies enabled us to envisage details about composition and genesis of beryl from the Eastern Desert of Egypt. Two types of beryl were investigated including emerald from ancient workings in the schist-related type whereas the other type is non-gem and granite-related. On the basis of FeOt-Cr2O3-MgO ternary classification, the Wadi El Gemal emeralds (alkali-type, sodic) are Mg-bearing while the Mikpid-Akarem beryls (normal-type) are Fe2+-bearing. Intense green colour of emerald results in a 323 cm−1 Raman shift due to ∼0.77 wt% Cr22O3 derived from serpentinite. In the Mikpid-Akarem district (belonging to the granite-related type), beryls are either faint blue or white and lack Cr, Mg and AlIV. On the other hand, they are relatively enriched in Fe and AlVI compared with the Wadi El Gemal emeralds (up to 0.13 & 1.97 apfu and 0.04 & 1.68 apfu, respectively), which is a function of the peraluminous composition of the granite host. Al3+ is substituted in the Y-site by di- to tetravalent cations (Mg2++Fe2++Cr3++Ti4+) and this is paired with a vacancy substitution by Na+. The Wadi El Gemal emeralds have H2O & K+ in the 2a-site and H2O & Na+ in the 2b-site. The latter site is vacant in the Mikpid-Akarem beryls.The FTIR spectra of our beryls and emeralds show a series of stretching and bending vibrations due to the presence of type I H2O (OH-Na band at 3657 cm−1) and type II H2O (stretching at 3591–3657 cm−1 & bending at 1631 cm−1). Lacking of Li+ leads to the absence of OH-Li band that is indicative of type III H2O. Hypothetical H2O in the Wadi El Gemal emerald (green beryl) amounts 2.24–2.92 wt% whereas it amounts 1.21–1.25 wt% in the Mikpid-Akarem non-green beryl. The asymmetric stretching vibration at 2921–2923 cm−1 is related to CH due to the presence of CH4, and possibly CO2, in the fluid inclusions trapped in the analyzed crystals. Some beryls, e.g. the Um Kabu emerald, has a Raman shift at 672 cm−1, which indicates maximal cation substitutions in the octahedral sites and minimal H2O in the channel sites. An uncommon shift at 147 cm−1 can be attributed to defect structure due to presence of radioactive zircon and monazite inclusions. Fe2+ substitution in the octahedral sites is appreciable and results in an UV–Vis-NIR band at 836 nm.

Aquamarine Gemstone

Aquamarine gemstone is one of the Beryl mineral varieties with Beryllium aluminium silicate composition. Its bluish green color caused from Fe2+ions puts it as a special variety. It is used in jewellery and has some industrial applications. This beautiful gemstone is reported from few countries only, namely India, Brazil, Canada, China, Italy, Pakistan, Russia, Ethiopia, Madagascar, Mozambique, Namibia, Nigeria, United Kingdom, United States, Mexico and Vietnam. The present study collected its occurrences from various parts of the world and studied the variation of oxides analyzed from Aquamarine. It is observed that SiO2 ranges from 64.99% to 72.48%, Al2O3:11.63% to 19.91%; BeO: 12.9% to 13.79%; FeO: 0.11% to 5.03%; CaO:0.01 %to 0.83%;MgO:0.00% to 1.93%; Na2O:0.10% to 3.53%; K2O:nearly zero to 3.31% and MnO:0.00% to 0.06%.

Recognition and Mapping of Structural Guides for Barytes Mineral Exploration in Parts of Kadapa District using Remote Sensing and GIS

Identification and mapping of structural criteria of a region reveals information about the occurrence of ore deposits of igneous and metamorphic origin. Remote Sensing and GIS data helps in detection of such structural features, like faults, lineament, folds, etc. These are important guides for exploration of ore mineral and groundwater. Kadapa district hosts important ore minerals of igneous and metamorphic origin like Barytes, asbestos, gold, galena, steatite etc. Barytes is exploited in the district since a long past. Present study is taken up to prepare structural map along the existing Barytes mines in the district using geospatial techniques like Remote Sensing and GIS, with an intension to identify new Barytes mineralized locations through these structural guides. The structural data of any region provides a quick payback with faster, more accurate mineral identification for gold, silver, diamonds, iron, nickel, copper, uranium, aluminum, Barytes, and also provide rock and mineral relationship in search for ore deposits during exploration. Structural criteria, is an important measure in mineral exploration of certain mineral deposits that are confined by geographic, geological and tectonic features. Mainly the occurrence of ore deposits is dependent on neighboring lithology and structural deformation of the location area. Endogenous mineral deposits like tin, muscovite, lithium, tungsten, gold, beryl, gemstones etc. are associated with intermediate and acid rocks like syenite; granite, granodiorite. etc., and deposits of copper, nickel, cobalt, silver, arsenic and apatite are formed in basic rocks like gabbro, norite, diorite, etc. Due to false nature of ore bodies and their varied controls of mineralization the techniques used for mineral exploration such as remote sensing followed by ground and airborne geophysical surveys, stream sediment, litho-geochemical surveys and core drilling have been used for regional and detailed surveys. The aspect that indicate the mineralisation are known as localizers. If these indicators can be identified on satellite data/imagery then the mineral explorations can be much faster with increased efficiency. Keywords: Multispectral, LISS-III Satellite Imagery, SOI Toposheet remote sensing, GIS Cite this Article Ramachandra M., Raghu Babu K., Pradeep Kumar B. et al. Recognition and Mapping of Structural Guides for Barytes Mineral Exploration in Parts of Kadapa District using Remote Sensing and GIS. Journal of Remote Sensing & GIS . 2018; 9(3): 30–36p.

Evaluation of Corrosion Resistance Properties of Aluminium 7075-Beryl Composite Materials in Acid Chloride Medium

Metal matrix composites are popular now a day due to the fact that their properties can be tailored by the addition of reinforcements like particulates, fibres and whiskers. Metal matrix composites show improved mechanical propertieswhen compared with those of matrix alloy. Improved ultimate tensile strength, hardness, percentage elongation, young’s modulus, impact strength and compression strength are shown by metal matrix composites. In the same way the corrosion resistance properties of composites are also improved over the same property of matrix alloy. Composites show improved weight loss corrosion resistance, stress corrosion resistance and polarisation studies. Hence the composites are important in the fields of aircraft, automobile and marine industries due to their increased life, improved mechanical and corrosion properties. In the present research work, aluminium 7075 alloy is selected as matrix and beryl or beryllium aluminium silicate is selected as reinforcement. Both are commercially available. Metal matrix composites containing different volume fraction of beryl particulates were successfully manufactured through liquid melt metallurgy technique using vortex method. Pre heated but uncoated beryl particulates of 50-80 micro meters are used in the manufacture of composites. Characterization studies were conducted on the aluminium 7075 alloy and its composites samples to evaluate the microstructural properties and corrosion properties. Microstructures were taken by using scanning electron microscope. Microstructural characterizations of composite samples reveal the presence and homogeneous distribution of beryl particulates. The corrosion tests conducted were static weight loss corrosion and potentiodynamic polarisation test using Elico make Potentiostat / galvanostat model CL95. Hydrochloric acid with different concentrated solutions usedas corrosion medium.Hydrochloric acid with three different concentrations of are used for the study. Corrosion current and corrosion rates were determined for matrix and composites in the above mentioned tests. In all the tests the composites decreased corrosion rate and decreased corrosion current when compared to those of matrix alloy. Hence composite materials are more suitable for the different applications than the matrix.

A NEW INVESTIGATION OF VIETNAM’S BERYL

The paper presents briefly new investigation of Vietnam beryl group, especially some characteristics of regional geology of Song Chay granite massif and new find of big crystals of beryl in them. The green beryl is found in quartz - mica - tourmaline, mica - feldspar – quartz pegmatite bodies in the south part of Song Chay granite - gneiss massif near Na Chi and Tan Nam villages, Quang Binh district, Ha Giang province.

北西パキスタン, モーマンド地方ブーチャ産エメラルドおよびグリーンベリル : 宝石鉱物

北西パキスタン, モーマンド地方ブーチャ産エメラルドおよびグリーンベリル : 宝石鉱物

Microstructural, Raman, EPMA and X-ray Tomographic Study of the Odisha's Beryl (Emerald) Sample

This study presents Optical, Microstructural, EPMA and X-ray tomography studies of the chromium-containing Beryl samples of Bangiriposi, Mayurbhanj district of Odisha. The detailed microscopic studies followed by EDAX analysis of different phases revealed the presence of beryllium aluminium silicate as the major matrix with yttrium silicate, Apatite, Albite, Quartz, Zircon, Cordierite and Ferichromite as minor inclusions. Micro-Raman data of the polished surface established the presence of gaseous (CO2, CH4), Water, and other Minerals. Few rare earth (lanthanides) elements such as Ce, Nd, Gd, Y and Sc, along with other transitional elements such as Ti and Zr, Cs are found to be present in these beryl samples. The volume percentage of silicate, phosphate, and oxide, as well as gaseous inclusions, are determined by X-ray tomographic study and are found to be 24%, 3.122% and 6.717% respectively.

Luminescence properties of precious beryl deposits

We studied the pulsed cathodoluminescence of beryls from several different mineral fields. We show that all green beryls, including emeralds, have a characteristic luminescence band in the 600–850 nm region; this band is produced by chromium and iron impurity ions. The individual spectroluminescence parameters for the beryls are the mean wavelength λ0, width σ, and intensity I of the band. We show that stones of the same mineral species (green beryl or emerald) from the same field form distinct, very nearly nonoverlapping groups in the phase space defined by the planar coordinates {λ0,σ,I}. This enables the field of origin for a stone to be determined based on its spectroluminescence parameters.

Milton's Gemstones and Precious Minerals: A Lapidary

Milton's Gemstones and Precious Minerals: A Lapidary

PEGMATITIC BERYL AS INDICATOR OF MELT EVOLUTION: EXAMPLE FROM THE VELASCO DISTRICT, PAMPEANA PEGMATITE PROVINCE, ARGENTINA, AND REVIEW OF WORLDWIDE OCCURRENCES

Fil: Sardi, Fernando Guillermo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Tucuman. Instituto Superior de Correlacion Geologica; Argentina

Genetic analysis of seed mineral accumulation affected by phosphorus deprivation in Brassica napus

The mineral content of plant seeds depends on both environmental and genetic factors. The aim of this study was to detect quantitative trait loci (QTLs), and their candidate genes, for the accumulation of phosphorus (P), calcium (Ca), magnesium (Mg), zinc (Zn), copper (Cu), iron (Fe), and manganese (Mn) in seeds of Brassica napus under normal and low P conditions using an F 10 recombinant inbred line (RIL) population. Two-year field trials were conducted to investigate seed mineral accumulation. The results showed a significant decrease in most of the minerals in the BE RIL population, as well as in two parental lines, when grown in a low P environment compared to a normal P environment. In total, 60 putative QTLs were identified, 33 of which overlapped with each other in nine genomic regions in seven linkage groups. Twenty-one of the 60 significant QTLs co-located with eight seed weight QTLs, and only five overlapped with three seed yield QTLs. Moreover, only six QTLs for the same minerals were identified both in normal and low P levels. By comparative mapping of Arabidopsis and B. napus, 148 orthologs of 97 genes involved in the homeostasis of the seven minerals in Arabidopsis were associated with 47 QTLs corresponding to 24 chromosomal regions. These results offer insight into the genetic basis of mineral accumulation across different P conditions in seeds of B. napus and allow the potential utilization of QTLs in biofortification.

Effects of Different Rootstocks and Cultivars on Yield and Some Yield Components of Grafted Tomato

This study was carried out to determine the effect of different rootstocks and cultivars on yield and certain yield characteristics of grafted tomato at the research greenhouse of horticultural department of Agriculture Faculty, Selcuk University, in 2007 and 2008. Gokce (191) F1, Beril F1 and Alida F1 hybrid cultivars were grafted on the rootstocks Rezistar, He-man and Spirit. The cultivars were trained to allow growth of two main stems while control group was pruned to leave one shot. According to the overall observations, 2007 and 2008 results of the study were similar. Among the cultivars Beril F1 had the highest yield as 162 280 kg ha-1, while it was followed by Heman and Spirit with the values of 161 640 kg ha-1and 158 190 kg ha-1, respectively. In terms of interaction, the highest yield was obtained from Heman x Beril F1 (190 490 kg ha-1) fallowed by Spirit x Beril F1 (181 050 kg ha-1). Beril F1 was the best cultivar based on investigated parameters and Heman and Heman x Beril gave the best results for rootstock and rootstock x cultivar interaction. Therefore, this cultivar and rootstocks could be recommended for the production.

UV optical absorption spectra analysis of beryl crystals from Brazil

The spectral decomposition analysis was applied to the optical absorption spectra of green and colorless beryl crystals from the Brazilian Eastern Pegmatitic province in the natural state, submitted to heat treatment and irradiated with UV light. The attributions of the lines were made taking into account highly accurate quantum mechanical calculations. The deconvolution of the green beryl spectra revealed four lines, two of them around 12,000 cm −1 (1.5 eV) and two of them around 34,000 cm −1 (4.2 eV) attributed to Fe 2+ and Fe 3+, respectively. The deconvolution of the colorless beryl spectra without any treatment, after heating and for the same heat treatment followed by UV light irradiation revealed five lines. The analysis of ratio relations showed that the lines at 36,400 cm −1 (4.5 eV) and 41,400 cm −1 (5.1 eV) belongs to a single defect attributed to a silicon dangling bond defect (Si:). Discussions and comparison with reported defects in quartz have supported the allocation of the lines at 61,000 cm −1 (7.6 eV) and 43,800 cm −1 (5.4 eV) to diamagnetic oxygen vacancy defect (Si–Si) and unrelaxed (Si⋯Si) defect, respectively. Finally, the line at 39,100 cm −1 (4.8 eV), quite polarized along the c-axis, was attributed to a (Fe 2+OH −) defect in the structural channels.

COMPORTAMENTO FÍSICO–QUÍMICO DO BERILO A ALTAS TEMPERATURAS

The thermal treatment is thoroughly used in beryl varieties with the objective to get better qualities of stones, or to modify the natural colour and, therefore, to get higher value for the gemstone. During the application of thermal treatment crystal chemistry changes of the mineral should be taken into account, so that not undesirable and irreversible modifications are produced. The physical and chemical qualities of 383 samples of yellow, blue, colourless, rose and green beryl were examined. The samples come from 16 different deposits from the Brazilian States of Minas Gerais, Paraiba, Rio Grande do Norte and Ceara. About 239 coloured and colourless samples were submitted to thermal treatments, and two colourless samples of goshenite were submitted to thermo-chemical or diffusion treatments. Change and/or uniformity of the colours were possible by means of the thermal treatments. For temperatures inferior to 800 o C or 900 o C, and depending on the variety and/or deposit, the beryl samples maintain their chemical compositions and physical properties macroscopically unchanged. However, at higher temperatures or in cases of longer treatment time, a possible phase transformation of the beryl occurred, which turns white and translucent, such as porcelain aspect.

The effect of thermal treatment on the 57Fe Mössbauer spectrum of beryl

Mossbauer spectra (MS) of blue, green and yellow beryl (ideally Be3Al2Si6O18) containing approximately 1% of iron were obtained at 295 and 500 K. Room temperature (RT) spectra of both blue and green samples showed the presence of an asymmetric Fe2+ doublet (ΔE Q~2.7 mm/s, δ~1.1 mm/s), with a very broad low-velocity peak. There is no clear evidence for the presence of a ferric component. The MS of the yellow sample at RT consists of an intense central absorption with parameters typical for Fe3+ (ΔE Q~0.4 mm/s, δ~0.29 mm/s), plus an apparently symmetrical Fe2+ doublet. This sample acquires a light-blue shade upon heating in air at about 620 K. Thermal treatments at high temperatures caused no significant changes in the MS, but the green and yellow beryl acquire a blue colour. All these results are interpreted in relation to the existence of channel water and the distribution of iron among the available crystallographic sites.

Oxidation effects in beryl induced by synchrotron radiation

Successive fluorescence-yield X-ray absorption near-edge structure spectra, collected within 30 s in quick-scan mode, show the extremely fast oxidation process of iron in natural, yellow and green beryl induced by synchrotron radiation. Initially, the Fe 3+/Fe 2+ ratio equals 0.52, which, with increasing time of exposure to the incident X-ray beam, increases to 2.03. The oxidation process starts about 5 min after exposure to the X-ray beam. From that moment on, after 30 s, the amount of ferric iron increases by ∼1.3%, implying that the exact amount of ferrous and ferric iron in beryl cannot precisely be determined when using the much slower, step-by-step scanning mode.

Growth and sector zoning in a beryl crystal

The structural defects and minor element concentrations of a beryl crystal from Brumado (Bahia, Brazil) were studied by X-ray diffraction topography and electron probe microanalysis. Examination showed that crystal growth was divided into two main stages, with significant differences with regard to defect density and variations in minor element concentrations, particularly Mg and Na. In the first growth stage, compositional variations and low defect density were observed; in the second stage, there was a decrease in impurity content and a sharp rise in defect density. Reconstruction of the growth history allowed the growth-sector boundaries to be located and related to compositional variations. In the first growth stage, minor element concentrations varied sharply when crossing the boundaries between the pinacoidal-pyramidal and pyramidal-prismatic growth sectors, whereas they decreased smoothly in the prismatic sector. They were therefore interpreted to be sector and chemical zonings respectively. Only chemical zoning was detected in the second stage of crystallisation.

Emerald and green beryl from Central Nigeria

Emerald and green beryl from Central Nigeria

Thermally stimulated depolarization currents in natural beryl

Abstract Thermally Stimulated Depolarization Current (TSDC) spectra of untreated pink, green and blue beryl samples show a single peak centered at 200 K, unaffected by heat and linearly dependent on the polarization field, a typical behaviour of defects with a dipolar origin. When the samples are thermally treated above 1000 K in air two new peaks appear at 170 K and 220 K. Above 1200 K water is removed from the channels of the beryl, the Fe2+ is reduced into Fe2+ and the formation of iron dipoles is then enhanced, giving rise to the observable bands. An increase in the peak height of the 170 K and the 220 K bands is observed when the samples are ultraviolet (UV) illuminated after the heat treatments. UV illumination of the samples leads to the photodissociation of hydroxyls followed by the displacement of the hydrogen to isolated sites, thereby contributing to the formation of iron dipoles.