Barite Mineralization Research Articles

Combination of Different Size Distributions for Mineral Particles by Applying Experimentally Determined Apparent Mean Shape Factor

As is well known, the behavior of systems of fine particles is strongly dependent on the size of the individual particles, and the size effects become increasingly important as the particles become progressively smaller. This study covers two different size analysis techniques, sieving and laser diffraction measurement, and constructs whole size distribution for different mill (ball and rod) products of some industrial minerals: barite and quartz minerals. A smooth overlap of corrected laser diffraction size distribution and sieve size distribution was obtained by applying the particle size with the apparent mean shape factor shifting to the right side of the curve for the rod-milled barite and ball- and rod-milled quartz. The apparent mean shape factors determined from the corrected particle size distributions were found to be 1.02 and 1.39 for ball- and rod-milled barite and 1.29 and 1.25 for ball- and rod-milled quartz, respectively. The results indicate that the ball-milled products of barite mineral have more regular (rounder in shape) particles than those of rod-milled barite, but there are not significant differences between the shape factors of ball- and rod-milled products of quartz mineral, i.e., both of them have irregular particles that deviate from spherical shape, as evident from the SEM pictures taken.

Stability and direct conversion of mineral barite crystals in carbonated hydrothermal fluids

The pseudomorphic replacement of mineral barite (BaSO4) crystals into barium carbonate was investigated in the present work by using carbonated alkaline hydrothermal fluids. Hydrothermal treatments were carried out over the temperature range from 150 up to 250 °C for intervals between 1 and 192 h, with different filling ratios (40–70%), and $$ {{\text{CO}}^{{2 - }}_{3} } \mathord{\left/ {\vphantom {{{\text{CO}}^{{2 - }}_{3} } {{\text{SO}}^{{2 - }}_{4} }}} \right. \kern-\nulldelimiterspace} {{\text{SO}}^{{2 - }}_{4} } $$ molar ratios of 1, 5, and 10. The reaction products were characterized by XRD and SEM techniques. The chemical reactivity of mineral barite crystals was markedly limited at temperatures below 200 °C, and only a tiny BaCO3 layer on the surface of the original BaSO4 crystal was formed on the crystal treated for 192 h. The rate of the pseudomorphic conversion of BaSO4 into BaCO3, was accelerated by increasing the reaction temperature and the molar ratio $$ {{\text{CO}}^{{2 - }}_{3} } \mathord{\left/ {\vphantom {{{\text{CO}}^{{2 - }}_{3} } {{\text{SO}}^{{2 - }}_{4} }}} \right. \kern-\nulldelimiterspace} {{\text{SO}}^{{2 - }}_{4} } $$ . Powder X-ray diffraction results showed that under hydrothermal conditions the replacement of $$ {\text{SO}}^{{2 - }}_{4} $$ ions by $$ {\text{CO}}^{{2 - }}_{3} $$ ions, in barite crystals was completed at 250 °C with a molar ratio $$ {{\text{CO}}^{{2 - }}_{3} } \mathord{\left/ {\vphantom {{{\text{CO}}^{{2 - }}_{3} } {{\text{SO}}^{{2 - }}_{4} }}} \right. \kern-\nulldelimiterspace} {{\text{SO}}^{{2 - }}_{4} } $$ = 10 for an interval of 192 h, resulting in the Witherite structure. The morphology of the completely converted BaCO3 at 250 °C in a Na2CO3 solution for 192 h, showed that the conversion proceed without severe changes of the original shape and dimension of the original crystal, similar to that observed in mineral pseudomorphic replacement process.

Barite-bearing cap dolostones of the Taoudéni Basin, northwest Africa: Sedimentary and isotopic evidence for methane seepage after a Neoproterozoic glaciation

The Taoudéni Basin of the West African craton contains one of the few genuine terrestrial records of a Neoproterozoic ice age. In the Adrar region of Mauritania, an extensive permafrost landscape, lithified moraines (tillites) and striated pavements are draped by a thin, generally <5-m thick dolostone, which is lithologically and isotopically similar to other basal Ediacaran cap dolostones worldwide. In Adrar, the cap carbonate unit exhibits a complex depositional history with significant lateral facies variation related to the irregular post-glacial, topographic relief and the complex interplay between glacioeustasy and isostatic rebound. The Adrar cap carbonate package consists of one or two dolostone units, with an intervening siliciclastic package of up to 40 m thickness, and a laterally extensive, thin limestone bed that disconformably overlies the uppermost dolostone. The cap dolostone comprises mechanically laminated beds that are disrupted by fitted-brecciation, sheet cracking, tepee formation, karstic dissolution and chaotic vein networks of silica, calcite and barite. The overlying thin bed of limestone breccia comprises volcaniclastic and detrital debris and authigenic barite crystals, cemented and commonly replaced by marine calcite. The close association between relative sea-level changes, glacier retreat and cap dolostone deposition across the Taoudéni Basin implies that cap dolostones formed largely over a period of ∼10 4 years, the maximum interval over which isostatic rebound is likely to operate. Barite has been reported from identical stratigraphic levels overlying terrestrial glacial deposits throughout NW Africa and formed locally during fluid mixing on, and in cavities beneath the seafloor during late stages of the post-glacial marine transgression. Samples of barite were collected from two distant localities in the Taoudéni Basin, in Mauritania and Mali. 87Sr/ 86Sr ratios exhibit an unusually narrow range for barite that closely matches contemporaneous seawater 87Sr/ 86Sr (0.7077–8). Barite δ 34S values range widely between 20‰ and 45‰ CDT, which indicates that sulphate derived from seawater and was subsequently modified by microbially mediated sulphate reduction. The consistent stratigraphic level and irregular distribution of barite deposits are consistent with a sedimentary exhalative origin for the barite, whereby Ba-rich fluids from shallow locations within the rock pile interacted with sulphate-bearing seawater; a hydrothermal origin for these fluids can be excluded. Isotopic constraints and the association of barite with terrestrial glacial deposits across the West African craton suggest that methane seepage from underlying permafrost may be one possible mechanism for Ba sequestration. The occurrence of seafloor barite precipitates at the contact between cap dolostones and overlying post-glacial limestones worldwide implies that changes in ocean composition, in particular increases in the sulphate content of ambient seawater provided an overriding control on barite mineralisation.

Structurally Controlled Vein Barite Mineralization in the Maritimes Basin of Eastern Canada: Geologic Setting, Stable Isotopes, and Fluid Inclusions

The Brookfield barite deposit occurs in the Carboniferous Maritimes basin of eastern Canada, an area known for ca. 300 Ma Mississippi Valley-type (MVT) Zn-Pb-Ba mineralization, including the past-producing Walton barite and Gays River Zn-Pb deposits. In contrast to most of MVT mineralization in the Maritimes Basin that is hosted by Visean carbonate rocks of the Windsor Group, the Brookfield deposit is hosted by red terrestrial clastics of the underlying Tournaisian Horton Group. The barite mineralization occurs as ≤25-m-wide fault fill with both coarse-textured, pristine barite and mylonitic-textured barite situated close to the Cobequid-Chedabucto fault system, separating the Meguma and Avalon terranes. The breccia vein mineralization has a simple mineralogy and consists of barite with up to 1.3 wt percent Sr, minor siderite, and trace amounts of late-stage quartz and calcite. The host rocks close to the barite mineralization are intensely altered, with quartz and kaolinite replacing muscovite and complete removal of diagenetic hematite. A Grant-type iso-con plot indicates mass loss (C A = 0.82*C O ) during wall-rock alteration with REE profiles maintained but relative chondrite-normalized abundances reduced. Although an Fe-Mn zone occurs a few 100 m along strike, no such mineralization occurs in the barite deposit. Fluid inclusion studies indicate that vein fluids were saline brines (20–30 wt % NaCl + CaCl 2 equiv) that co-existed with an immiscible N 2 -CO 2 -CH 4 gas. Laser Raman analysis of the most common gas-rich inclusions indicates a uniform fluid chemistry with 66 mol percent N 2 and 34 mol percent CO 2 and is consistent with compositions inferred from thermometric measurements. Homogenization temperatures for primary, aqueous fluid inclusion asemblages in quartz intergrown with barite indicate minimum trapping temperatures of 210°C. Conditions at the time of entrapment, based on intersection of aqueous and gaseous isochores, are estimated at ~775 bars and 250°C. Stable isotope data for vein minerals (barite, siderite, quartz) are uniform in nature and indicate δ 18 O fluid = +12 per mil at 250°C for siderite and +9.8 per mil for quartz, δ 13 C fluid = −4 to −6 per mil from siderite, and δ 34 S fluid = +12 per mil from barite. Fluid inclusion extracts indicate δD values of −47 to −71 per mil. Collectively, these isotopic compositions are consistent with a basinal-type fluid derived from modified meteoric water with sulfur derived from Carboniferous evaporites and carbon of mainly marine limestone origin (i.e., Carboniferous Windsor Group) with a minor biogenic component from the Horton Group. Mineralization at Brookfield resulted from focusing of heated, overpressured brines of modified basinal origin into an active fault zone environment. The association of the barite mineralization with intensely altered wall rock represents a rare example of such alteration in the MVT metallogenic domain of the Maritimes Basin. However, similar alteration associated with Ba-Fe-Mn mineralization along the Cobequid-Chedabucto fault system raises the possibility that the Brookfield deposit may instead be part of another mineralizing event that was distinct from the 300 Ma MVT deposits.

C, O, S and Sr isotope studies on the genesis of Fe-carbonate and barite mineralizations in the Attepe iron district (Adana, Southern Turkey)

The Attepe district consists of Precambrian, Lower–Middle Cambrian, Upper Cambrian–Lower Ordovician and Mesozoic formations. It contains several iron deposits and occurrences. Three types of iron-mineralizations can be distinguished in the area; (i) Sedimentary Fe-sulfide in Precambrian bituminous metapelitic rocks, and Fe-oxides in Precambrian metasandstones (SISO), (ii) vein-type Fe-carbonate and oxides composed of mainly siderite, ankerite and hematite including barite in Lower–Middle Cambrian metacarbonates of the Çaltepe Formation (HICO), (iii) karstic Fe-oxides and hydroxides essentially in the Lower–Middle Cambrian metacarbonates and the unweathered Fe-carbonates (KIO). The latter type is more widespread and located at the upper parts of the most important mineable iron deposits like Attepe deposit. Oxygen-, carbon-, sulfur- and strontium-isotope studies have been performed on siderites and barites in the vein-type ores, and on calcites in the recrystallized Çaltepe Limestones to investigate the sources and formation mechanism of primary ore-forming constituents. The δ 13C values of siderites and calcites in limestones of the Çaltepe Formation range from −10.10‰ to −8.20‰, and from −0.8‰ to 2.30‰. Both carbonate minerals show δ 18O values between 17.50–18.30‰ and 16.20–23.00‰, respectively. The δ 13C and δ 18O isotopic variations do not indicate any direct or linear relations between siderites and limestones. However, it is possible that the carbon and oxygen isotopic compositions of carbonate minerals could be changed to some extent, when limestones were subjected to hydrothermal processes or thermal alterations during metamorphism. The isotopic values of barites display 32.40–38.30‰ for δ 34S and 12.20–14.70‰ for δ 18O. The strontium isotope ratios (0.717169–0.718601) of barites and the sulfur isotope compositions of barites and pyrites suggest that there are no direct linkages of ore-forming compounds neither with a magmatic source nor with sedimentary pyrite formations in the Precambrian bituminous shales of the Attepe formation. According to the field observations and the stable isotope data, siderites and ankerites should be formed by interaction between iron-rich hydrothermal fluids and Çaltepe limestones, whereas isotope ratios of barites indicate that they were formed by mixing of sulfur-rich meteoric waters and deeply circulated hydrothermal solutions.

Cenozoic “radiobarite” occurrences in the Ohře (Eger) Rift, Bohemian Massif: Mineralogical and geochemical revision

Barite occurrences related to the Cenozoic (Late Alpine) low-temperature hydrothermal activity are present in the continental Ohře (Eger) Rift area. A specific, Ra-bearing type of barite has been known under the name “radiobarite” from this area since 1904. Revision of 12 localities revealed the presence of alleged radiobarite only in the Teplice (Lahošť–Jeníkov) and Karlovy Vary areas. Barite from other localities is radium-poor. Barite crystals showing concentric oscillation colour zoning totally prevail. Isomorphous substitution of Sr ( X×10 −1 to X×wt%), Ca ( X×10 −2 wt%) and Fe ( X×10 −1 wt%) for Ba was proved. Average SrO contents of 0.4 wt% are markedly exceeded in some samples from Lahošť–Jeníkov (max. 3.2 wt%) and Karlovy Vary (max. 4.9 wt%). Besides inclusions of stoichiometric iron disulphide, the same samples also contain iron disulphides with unusual high contents of Co (max. 12.2 wt%) and Ni (max. to 8.4 wt%). Specific activity of 238U in the studied barites is very low while that of 226Ra reaches 8 Bq/g in several samples. Therefore, 226Ra is not in equilibrium with its parent uranium. These “radiobarites” or their parts must be therefore relatively young, not older than 10–15 ka. Very low uranium contents (<0.4 ppm) were also confirmed by neutron activation analyses of barite samples. Unit-cell dimensions refined from X-ray powder diffraction data do not show any systematic variation with the measured chemical composition. Their values agree with the data given in the literature. Reflection half-widths, however, seem to correlate with chemistry. Peaks are wider in samples from Lahošť–Jeníkov and Karlovy Vary. Sulphur and oxygen stable isotope compositions of the Cenozoic barite mineralization of Teplice area are very uniform ( δ 34S values between 3.9‰ and 7.1‰ CDT, and δ 18O values between 6.1‰ and 7.7‰ SMOW), while the barites of Děc˘ín area show more variable sulphur sources. Sulphate derived from sediments of the Tertiary Most Basin seems to dominate for the Teplice area, while Cretaceous sediments are a more probable sulphur source in the Děc˘ín area. Calculation of oxygen isotope composition of hydrothermal fluids based on fluid inclusion homogenization temperatures and barite δ 18O data shows δ 18O fluid values in the range of meteoric waters or δ 18O – shifted deep circulating meteoric or basinal waters.

The development of volcanic hosted massive sulfide and barite–gold orebodies on Wetar Island, Indonesia

Wetar Island is composed of Neogene volcanic rocks and minor oceanic sediments and forms part of the Inner Banda Arc. The island preserves precious metal-rich volcanogenic massive sulfide and barite deposits, which produced approximately 17 metric tonnes of gold. The polymetallic massive sulfides are dominantly pyrite (locally arsenian), with minor chalcopyrite which are cut by late fractures infilled with covellite, chalcocite, tennantite–tetrahedrite, enargite, bornite and Fe-poor sphalerite. Barite orebodies are developed on the flanks and locally overly the massive sulfides. These orebodies comprise friable barite and minor sulfides, cemented by a series of complex arsenates, oxides, hydroxides and sulfate, with gold present as <10 μm free grains. Linear and pipe-like structures comprising barite and iron-oxides beneath the barite deposits are interpreted as feeder structures to the barite mineralization. Hydrothermal alteration around the orebodies is zoned and dominated by illite–kaolinite–smectite assemblages; however, local alunite and pyrophyllite are indicative of late acidic, oxidizing hydrothermal fluids proximal to mineralization. Altered footwall volcanic rocks give an illite K–Ar age of 4.7±0.16 Ma and a 40Ar/39Ar age of 4.93±0.21 Ma. Fluid inclusion data suggest that hydrothermal fluid temperatures were around 250–270°C, showed no evidence of boiling, with a mean salinity of 3.2 wt% equivalent NaCl. The δ34S composition of sulfides ranges between +3.3‰ and +11.7‰ and suggests a significant contribution of sulfur from the underlying volcanic edifice. The δ34S barite data vary between +22.4‰ and +31.0‰, close to Miocene seawater sulfate. Whole rock 87Sr/86Sr analyses of unaltered volcanic rocks (0.70748–0.71106) reflect contributions from subducted continental material in their source region. The 87Sr/86Sr barite data (0.7076–0.7088) indicate a dominant Miocene seawater component to the hydrothermal system. The mineral deposits formed on the flanks of a volcanic edifice at depths of ~2 km. Spectacular sulfide mounds showing talus textures are localized onto faults, which provided the main pathways for high-temperature hydrothermal fluids and the development of associated stockworks. The orebodies were covered and preserved by post-mineralization chert, gypsum, Globigerina-bearing limestone, lahars, subaqueous debris flows and pyroclastics rocks.

Stratiform coticule-barite-sulphide horizons in the sediment-hosted Tsongoari-Omupokko Pb-Cu-Ba-Zn-Ag prospects, Kaokoland, Namibia

At Tsongoari-Omupokko, in the southern Kaoko Belt of northwestern coastal Namibia, several metamorphosed coticule, iron formation and massive barite horizons with minor base metal sulphides are hosted by Late Proterozoic clastic to chemical sediments of the Ugab Subgroup, Damara Sequence. The depositional conditions of the host rocks were variable with environments changing from playa lacustrine, to coastal or shallow marine, to submarine turbiditic and deep marine. Hydrothermal activity is confined to metapelitic and metapsammitic rocks above carbonate layers. The mineralised units of the Pb-Cu-Ba-Zn-Ag prospects vary considerably in their modal composition and to a lesser extent in their thickness and overall mineral content. Vertical changes of mineralogy and geochemistry indicate rhythmic exhalative cyclicity. Associated mica schist and feldspar-bearing quartzite host rock contains Mn- and Cu-bearing biotite and muscovite, Zn-bearing amphibole, hyalophane, fluorite and apatite.At Tsongoari West, mineralisation consists of euhedral spessartine-rich garnet and magnetite in a matrix of manganoan amphibole, quartz, mica and carbonate. Considerable amounts of primary galena and secondary Cu-carbonate occur at the base of the mineralised horizon at the transition to the meta-pelites. At Tsongoari East and Omupokko, aggregates of galena, chalcopyrite, digenite and sphalerite occur in laterally and vertically consistent massive barite, magnetite and coticule horizons, which have a maximum thickness of 10m and a length of 4.5 kilometres. Secondary biotite and amphibole are similarly enriched in trace elements as at Tsongoari West. Lateral thinning of the mineralised horizons occurs over 10’s of metres. Sharp contacts of the mineralised horizons with the hanging wall and footwall suggest rapid transition from exhalative to detrital sedimentation. Barite and Mn-silicate mineralisation are regarded as the more distal exhalative facies types relative to a potential fluid discharge site and indicate variable oxidation and pH conditions during submarine hydrothermal activity. Field evidence points towards a laterally uniform hydrothermal-sedimentary depo-environment within the unfolded Tsongoari/Omupokko lithologies, where mineralisation was shaped by the relief of the sedimentary palaeo-surface. Fluid inclusion data from barite and quartz mineralised zones yielded medium temperatures (150° to 280°C) and medium salinity (3 to 7% NaCl-equivalent), characteristic of fluid compositions which are influenced by mixing with meteoric fluids during recrystallisation processes. Sulphur isotope ratios between 13 and 16‰ δ 34 S for sulphide and 26‰ for sulphate at Tsongoari East, and −7‰ δ 34 S for sulphide and 9.5‰ for sulphate at Tsongoari West indicate overall strong seawater sulphur input. During Damaran Orogeny (~550 to ~490 Ma), strong compressional nappe- to thrust-dominated deformation metamorphosed the mineralised sections to lower amphibolite-grade facies (~550 to ~610° C at ~6.5 to ~9kbar) as indicated by mineral assemblages in the coticules, without significantly effecting primary geochemical profiles.

The Pierina epithermal Au–Ag deposit, Ancash, Peru: paragenetic relationships, alunite textures, and stable-isotope geochemistry

The Pierina high-sulfidation epithermal Au–Ag deposit (9°26.5′S; 77°35′W) was emplaced in the Middle Miocene into a hypabyssal-to-extrusive “pumice-tuff” and an underlying, older, dacitic flow-dome complex, both of which are cut by hydrothermal breccias and small dacitic domes. Stage I advanced argillic alteration generated a core of vuggy silica, focused in the tuff, and surrounded successively by zones of quartz–alunite, dickite±kaolinite±pyrophyllite, and illite–montmorillonite±kaolinite. Laser-ablation ICP-MS analysis of the sulfide minerals of the succeeding, Stage II, Cu (–Pb, Bi, Sb, Zn, As)–barite mineralization, largely confined to the vuggy-silica zone, reveals that both Au and Ag were introduced at that time. This assemblage was almost entirely obliterated during Stage III, when oxidation by low-temperature meteoric waters generated botryoidal hematite–goethite assemblages, which are now the main precious-metal hosts. Stage IV barite–acanthite mineralization shows limited temporal overlap with Stage III, but dominantly overprints the hematite–goethite assemblage. The deposit incorporates alunite exhibiting a wide range of modes of occurrence, grain size, and morphology. Disseminated alunite dominates Stage I alteration, which replaced phenocrysts and fragments, and locally hosts corroded, ≤40 μm alumino-phosphate-sulfate (APS) inclusions. The alunite shows limited Na substitution [molar Na/(Na+K)=<0.2], but alunite–natroalunite assemblages occur sporadically throughout the quartz–alunite alteration zone. Isotopic analysis yields δ 34S values of 16.6–31.0‰, consistent with a magmatic–hydrothermal origin. Rare occurrences of disseminated alunite and pyrite in textural equilibrium occur in unoxidized areas of the deposit, and yieldΔ 34S alu-py precipitation temperatures of 179 to 250 °C, with the majority below 200 °C. Disseminated alunite in shallower, oxidized portions of the deposit, where pyrite has been destroyed, yield δ 18O SO 4 values of 6.3‰ to 14.4‰. The lighter compositions occur along the axis of the quartz–alunite alteration zone, and imply precipitation at higher temperatures, albeit with some meteoric water involvement. Porcelaneous alunite (10–100 μm) forms the matrix of breccias that cut Stage I alteration. Sodium contents are low [Na/(Na+K molar≃0.1) and APS inclusions have not been identified. The δ 34S values of 21.8–27.1‰ are consistent with a magmatic–hydrothermal origin, but the δ 18O SO 4 values of 11.4‰ to 14.6‰ indicate deposition under cooler temperatures and the involvement of meteoric water that interacted substantially with igneous country-rocks. Coarse, open-space-filling alunite, which occurs as veins or coatings on breccia fragments, exhibits limited Na substitution, is not associated with natroalunite, and does not host APS inclusions. Its δ 34S and δ 18O SO 4 values of 12.9‰ to 26.2‰ and 6.5‰ to 8.6‰, respectively, imply a magmatic–hydrothermal origin and deposition at higher temperatures. Dike-like bodies and mantos of friable alunite have distinctive δ 34S (16.2–19.3‰) and δ 18O SO 4 (7.6–9.2‰) values, and may record a steam-heated environment. However, these compositions may also indicate loss of H 2S gas during oxidation, or overprinting of steam-heated alunite by magmatic–hydrothermal alunite (or vice versa). All forms of alunite exhibit higher δ 18O SO 4 values in the central part of the deposit, and the coherent isotopic chemistry casts doubt on the reliability of the widely accepted textural criteria for the origin of this mineral in hydrothermal systems.

Long-lived activation products in TRIGA Mark II research reactor concrete shield: calculation and experiment

In this paper, a process of long-lived activity determination in research reactor concrete shielding is presented. The described process is a combination of experiment and calculations. Samples of original heavy reactor concrete containing mineral barite were irradiated inside the reactor shielding to measure its long-lived induced radioactivity. The most active long-lived (γ emitting) radioactive nuclides in the concrete were found to be 133Ba, 60Co and 152Eu. Neutron flux, activation rates and concrete activity were calculated for actual shield geometry for different irradiation and cooling times using TORT and ORIGEN codes. Experimental results of flux and activity measurements showed good agreement with the results of calculations. Volume of activated concrete waste after reactor decommissioning was estimated for particular case of Jožef Stefan Institute TRIGA reactor. It was observed that the clearance levels of some important long-lived isotopes typical for barite concrete (e.g. 133Ba, 41Ca) are not included in the IAEA and EU basic safety standards.

The appraisal of a proposed barite quarry in Akpet Area, Cross River State, from resistivity investigation

Electrical resistivity survey was done at a site at Akpet area, Cross River State to evaluate the subsurface for barite mineralization. Both vertical electrical sounding (VES) and horizontal resistivity profiling (HRP) were performed in conjunction with surface geological mapping in the area. In both VES and HRP, the Schlumberger electrode array was adopted and measured resistivity data interpreted using conventional curve matching techniques and iterative computer modelling. Results show that three (3) zones designated A, B and C with barite mineralization occur within a depth of 5m in the subsurface at the project site. The combined high specific gravity of 4.4 g/cc and high BaSO4 (>92%) show that the barite of the study area are of high quality. The practical recovery of over 8 tons of barite at the project site shortly after this report which revealed the occurrence of large deposit of barite in the area; show that the applicability of the resistivity method in the search of barite and other minerals alike is very reliable. KEY WORDS: Barite, resistivity, subsurface, recovery. Global Journal of Geological Sciences Vol.2(2) 2004: 171-175

Regional tectonic effects on the composition and mode of distribution of barite mineralization in Akpet Area, SE Nigeria

Reconnaissance geologic mapping for barite mineralization within Akpet Central and environs had been successfully done. The results of the study show that the mineralization of barite is largely structurally controlled although minor sedimentary processes have also contributed. Barite mineralization in the area therefore probably displays both metamorphic/igneous and/or sedimentary origins. Those that are derived from igneous processes occur mainly as veins and exhibit thicknesses which depend on the width of the fractures found in the rocks. On the other hand, barite mineralisation in the northeastern flank of the study area occurs as alluvial deposits and in few cases as domes. Chemical compositions for samples obtained from the northwestern and southwestern parts of the area show greater concentration of BaSO4 than in those samples from northeastern axis which exist in alluvial forms. Hence, both regional tectonic activities and the mode of occurrence of barites constitute important factors in the evaluation of barite mineralization. All the barite samples of the study areas analyzed are of high quality to stand the test of time in the world market. KEY WORDS: Mineralization; Barite; Fractures; quality; alluvial. Global Journal of Geological Sciences Vol.2(2) 2004: 177-181

POSSIBLE SUBMARINE ADVANCED ARGILLIC ALTERATION AT THE BASIN LAKE PROSPECT, WESTERN TASMANIA, AUSTRALIA

The Basin Lake copper-gold prospect lies in western Tasmania’s Mount Read Volcanics and is hosted in a series of calc-alkaline andesites, quartz-feldspar porphyries, mudstones, carbonates, and sandstones between the Tyndall Group and the Central Volcanic Complex. Alteration at the Basin Lake prospect occurs over a strike length of 1.4 km and includes thin, strata-bound pyrophyllite-quartz-paragonite-kaolinite-pyrite-alunite alteration zones, up to 12 m wide and containing up to 50 wt percent pyrophyllite, with local fluorite veining. These zones grade out to paragonite-muscovite-kaolinite-quartz-pyrite and muscovite-carbonate-chlorite alteration zones. Extensive propylitic alteration (chlorite-carbonate-epidote) affects most other rocks outside these zones. Mineralization consists of thin strata-bound zones of massive and vein pyrite, tennantite, and chalcopyrite, with trace covellite and galena, hosted mainly within an intensely silicified core of the pyrophyllite-quartzsericite alteration zone. Pyrite has δ34S values of –1.4 to +6.9 per mil, although marginal vein pyrite in the propylitic zone has δ34S values around 12.4 per mil. Large silicified glacial erratic boulders at surface contain massive and vein pyrite, enargite, and tennantite, with minor barite, and trace covellite, stannoidite, and mawsonite. Pyrite and enargite have δ34S values of 1.7 to 6.8 per mil; barite has δ34S values around 35.2 per mil with 87Sr/86Sr around 0.7108. The alteration and mineralization at the Basin Lake prospect is similar to that associated with high-sulfidation copper-gold systems formed by acidic, relatively oxidized fluids. A new geochemical vector, here termed the “advanced argillic alteration index” [AAAI = 100 (SiO2)/(SiO2 + 10MgO + 10CaO + 10Na2O)], has been devised to help quantify the intensity of alteration. The values of the AAAI at Basin Lake are similar to those of several high-sulfidation epithermal deposits. The low sulfide δ34S values are similar to those at other sulfide occurrences in the Mount Read Volcanics that have previously been considered to be barren, are lower than those of nearby volcanic-hosted massive sulfide deposits, and may indicate a magmatic fluid component. However, the δ34S and 87Sr/86Sr values of Basin Lake barite at the assumed highest exposed level of the system and higher δ34S values in pyrite from marginal veins are similar to those of Cambrian volcanic-hosted massive sulfide systems, indicating the involvement of reduced seawater sulfate at these locations. Calcite carbon and oxygen isotope values, silicate oxygen isotope values, and the unusual abundance of carbonate close to advanced argillic alteration indicate fluid mixing and suggest that acidic, magmatic fluids were likely neutralized by seawater. This occurrence strengthens the case for prospecting the Mount Read Volcanics and other similar submarine volcanic belts for copper-gold and gold-only deposits that formed by the actions of hyperacid oxidized fluids.

Determination of the critical surface tension of wetting of minerals treated with surfactants by shear flocculation approach.

This paper contributes the shear flocculation method as a new approach to determine the critical surface tension of wetting of minerals treated with surfactants. This newly developed approach is based on the decrease of the shear flocculation of the mineral suspension, with decreasing of the surface tension of the liquids used. The solution surface tension value at which shear flocculation does not occur can be defined as the critical surface tension of wetting (gamma c) of the mineral. By using the shear flocculation method, the critical surface tensions of wetting (gamma c) for calcite and barite minerals, treated with surfactants, were obtained as 30.9 and 35.0 mN/m, respectively. These values are in good agreement with data reported previously on the same minerals obtained by the contact angle measurement and flotation methods. The chemical agents used for the treatment of calcite and barite particles were sodium oleate and sodium dodecyl sulfate, respectively.

Industrial radioactive barite scale: suppression of radium uptake by introduction of competing ions

Incorporation of radioactive isotopes during the formation of barite mineral scale is a widespread phenomenon occurring within the oil, mining and process industries. In a series of experiments radioactive barite/celestite solid solutions (SS Barite–Celestite) have been synthesized under controlled conditions by the counter diffusion of 226Ra, Ba 2+, Sr 2+ and SO 4 2− ions through a porous medium (silica gel), to investigate inhibiting effects in Ra uptake associated with the introduction of a competing ion (Sr 2+). From characterization studies, the particle size and the morphology of the crystals appear to be related to the initial [Sr]/[Ba] molar ratio of the starting solution. Typically, systems richer in Sr produce smaller sized crystals and clusters characterized by a lower degree of order. The activity introduced to the system is mainly incorporated in the crystals generated from the barite/celestite solid solution as suggested by the activity profiles of the hydrogel columns analysed by γ-spectrometry. There is a relationship between the initial [Sr]/[Ba] molar ratio of the starting solution and the activity exhibited by the synthesized crystals. An effective inhibition of the 226Ra uptake during formation of the crystals (SS Barite–Celestite) was obtained through the introduction of a competing ion (Sr 2+): the higher the initial [Sr]/[Ba] molar ratio of the starting solution, the lower the intensity of the activity peak in the crystals.

Strontium isotopic signature of hydrothermal sedimenta-tion from Early Cambrian barite deposits in east Guizhou, China

The ore genesis model for barite deposits in east Guizhou Province has been in dispute and the major debate focuses on whether they are product of the submarine hydrothermal sedimentation. This note presents new strontium isotope data from 19 samples of Dahebian and Yuping barite deposits, and their 87Sr/86Sr ratios are significantly lower than that of the coeval seawater. The 87Sr/86Sr ratios of 17 samples out of 19 samples rang from 0.708310 to 0.708967, indicating that they might be related to the mantel admixture. Two isotopic ratios in this study are higher than those of coeval seawater (0.7090), collected from late-stage barite mineral vein of interpenetrative strata and a barite nodule bearing hypidiomorphic granular pyrite, which indicates that they might be related to the continental admixture. The study provides Sr isotopic evidence not only for the submarine hydrothermal exhalative genesis of Dahebian and Yuping barite deposits, but also for distinguishing the barite mineralization of late stage.

Mineralogy and Geochemistry of an Epithermal Manganese District, Sierras Pampeanas, Argentina

The manganese mineralization studied in this paper represents the major concentration of this element in Argentina. It occurs in an area of 70 x 30 km, in the Sierras Pampeanas ranges, located in the provinces of Córdoba and Santiago del Estero. The analyzed area represents about 30% of the entire mineralized system. It is quite unusual because it is hosted in granodioritic and rhyodacitic rocks. Geochemical, petrological, and structural analyses demonstrate that these rocks are unrelated to the mineralization. The geometry and distribution of the veins are mainly controlled by faults, where the manganese is found mainly as fault-breccia cement. These faults are the result of a dextral shear system that produced Riedel-type structures related to N-S lineaments. Textural and structural analyses of the veins indicate four deformational events. Ore minerals precipitated during the first three events, whereas the gangue was mainly formed during the last episode. X-ray diffraction and microprobe studies show that Mn4+ oxides (hollandite, pyrolusite, ramsdellite, romanèchite, cryptomelane, and coronadite) associated with Fe3+ oxides (goethite and hematite) are the ore minerals. The gangue consists of calcite, opal, and lesser amounts of barite, fluorite, and clay minerals. The studied area represents shallow levels of an epithermal ore deposit; hence, it is possible to predict that these veins may continue to deeper levels.

Multistage Hydrothermal Silicification and Fe-Tl-As-Sb-Ge-REE Enrichment in the Red Dog Zn-Pb-Ag District, Northern Alaska: Geochemistry, Origin, and Exploration Applications

Geochemical analyses of major, trace, and rare earth elements (REE) in more than 200 samples of variably silicified and altered wall rocks, massive and banded sulfide, silica rock, and sulfide-rich and unmineralized barite were obtained from the Main, Aqqaluk, and Anarraaq deposits in the Red Dog Zn-Pb-Ag district of northern Alaska. Detailed lithogeochemical profiles for two drill cores at Aqqaluk display an antithetic relationship between SiO2/Al2O3 and TiO2/Zr which, together with textural information, suggest preferential silicification of carbonate-bearing sediments. Data for both drill cores also show generally high Tl, Sb, As, and Ge and uniformly positive Eu anomalies (Eu/Eu* >1.0). Similar high Tl, Sb, As, Ge, and Eu/Eu* values are present in the footwall and shallow hanging wall of Zn-Pb-Ag sulfide intervals at Anarraaq but are not as widely dispersed. Net chemical changes for altered wall rocks in the district, on the basis of average Al-normalized data relative to unaltered black shales of the host Kuna Formation, include large enrichments (>50%) of Fe, Ba, Eu, V, S, Co, Zn, Pb, Tl, As, Sb, and Ge at both Red Dog and Anarraaq, Si at Red Dog, and Sr, U, and Se at Anarraaq. Large depletions (>50%) are evident for Ca at both Red Dog and Anarraaq, for Mg, P, and Y at Red Dog, and for Na at Anarraaq. At both Red Dog and Anarraaq, wall-rock alteration removed calcite and minor dolomite during hydrothermal decarbonation reactions and introduced Si, Eu, and Ge during silicification. Sulfidation reactions deposited Fe, S, Co, Zn, Pb, Tl, As, and Sb; barite mineralization introduced Ba, S, and Sr. Light REE and U were mobilized locally. This alteration and mineralization occurred during Mississippian hydrothermal events that predated the Middle Jurassic-Cretaceous Brookian orogeny. Early hydrothermal silicification at Red Dog took place prior to or during massive sulfide mineralization, on the basis of the dominantly planar nature of Zn-Pb veins, which suggests filling of fractures that developed in previously lithified rock. Uniformly low Ca and Mg and uniformly negative Ce anomalies in highly siliceous Red Dog wall rocks reflect hydrothermal decarbonation reactions and pervasive silicification owing to conductive cooling of oxidized metalliferous fluids. Similar Ca and Mg depletions are evident at Anarraaq but generally lack associated silicification, possibly because temperatures of the hydrothermal fluids were too low (<180°C) or because the thermal contrast between the fluids and wall rocks was smaller owing to the greater depth of alteration and mineralization there, compared with Red Dog. Chalcophile element anomalies (Fe, Zn, Pb, Tl, As, Sb) in wall rocks at both Red Dog and Anarraq are attributed to sulfidation reactions, coeval with subsurface Zn-Pb-Ag mineralization, during the mixing of oxidized metalliferous fluids with H2S-rich fluids derived locally within the Kuna Formation. Sedimentary wall rocks in the Red Dog district are characterized by a distinctive suite of geochemical anomalies, especially for Zn, Pb, Tl, As, Sb, Ge, and Eu/Eu*. At the Aqqaluk deposit, wall rocks without visible sphalerite or galena (<300 ppm Zn + Pb) have anomalous Eu/Eu*, Tl, Sb, and As for up to ~100 m stratigraphically below Zn-rich silica rock. At Anarraaq, the Tl anomaly is most extensively developed, and enrichment relative to unaltered black shale of the Kuna Formation is present up to 62 m above the highest Zn-Pb sulfide zones. The magnitude of the enrichment and systematic behavior of Tl in the district make Tl a promising geochemical exploration guide for Red Dog-type Zn-Pb-Ag deposits elsewhere.

Variation of critical surface tension for wetting of minerals with roughness determined by Surtronic 3+ instrument

This paper presents a correlation found between the surface roughness and critical surface tension of wetting of calcite and barite minerals. The minerals were ground in ball, rod and autogenous mills to collect samples for further tests (i.e. roughness and wettability). The surface roughness values of those minerals were determined on the pelleted surfaces of the ground powders by employing Surtronic 3+ roughness-meter instrument. The contact angle measurements were also made by a goniometer on these pellets in order to determine the critical surface tension of wetting of calcite and barite minerals. From the experimental work, it is stated that the wettability degree of calcite and barite minerals increase with their increasing surface roughness. The relationships could be stated as: γc=aRa+b type of equations; where γc is the critical surface tension of wetting, Ra is the surface roughness measured, a is the slope and b is the intercept of the regression line.

Variation of critical surface tension for wetting of minerals with roughness determined by Surtronic 3 + instrument

This paper presents a correlation found between the surface roughness and critical surface tension of wetting of calcite and barite minerals. The minerals were ground in ball, rod and autogenous mills to collect samples for further tests (i.e. roughness and wettability). The surface roughness values of those minerals were determined on the pelleted surfaces of the ground powders by employing Surtronic 3 + roughness-meter instrument. The contact angle measurements were also made by a goniometer on these pellets in order to determine the critical surface tension of wetting of calcite and barite minerals. From the experimental work, it is stated that the wettability degree of calcite and barite minerals increase with their increasing surface roughness. The relationships could be stated as: γ c= aR a+ b type of equations; where γ c is the critical surface tension of wetting, R a is the surface roughness measured, a is the slope and b is the intercept of the regression line.