Textural characterization and heavy mineral studies of beach sediments in Ibeno and Eastern Obolo Local Government Areas of Akwa Ibom State were carried out in the present study. The main aim was to infer their provenance, transport history and environment of deposition. Sediment samples were collected at the water–sediment contact along the shoreline at an interval of about 3m. Ten samples were collected from study location 1 (Ibeno Beach) and twelve samples were collected from study location 2 (Eastern Obolo Beach). A total of twenty–two samples were collected from the field and brought to the laboratory for textural and compositional analyses. The results showed that the value of graphic mean size ranged from 1.70Ф to 2.83Ф, sorting values ranged from 0.39Ф – 0.60Ф, skewness values ranged from -0.02 to 0.10 while kurtosis values ranged from 1.02 to 2.46, indicating medium to fine grained and well sorted sediments. This suggested that the sediments have been transported far from their source. Longshore current and onshore–offshore movements of sediment are primarily responsible in sorting of the heavy minerals. The histogram charts for the different samples and standard deviation versus skewness indicated a beach environment of deposition. This implies that the sediments are dominated by one class of grain size; a phenomenon characteristic of beach environments. The heavy mineral assemblages identified in this research work were rutile, zircon, tourmaline, hornblende, apatite, diopside, glauconite, pumpellyite, cassiterite, epidote, garnet, augite, enstatite, andalusite and opaque minerals. The zircon-tourmaline-rutile (ZTR) index ranged from 47.30% to 87.00% with most of the samples showing a ZTR index greater than 50%. These indicated that the sediments were mineralogically sub-mature and have been transported far from their source. The heavy minerals identified are indicative of being products of reworked sediments of both metamorphic (high rank) and igneous (both mafic and sialic) origin probably derived from the basement rocks of the Oban Massif as well as reworked sediments of the Benue Trough. Therefore, findings from the present study indicated that erosion, accretion, and stability of beaches are controlled by strong hydrodynamic and hydraulic processes.

Adsorption of lead(II) as a major heavy metal pollutant onto nano-adsorbents of Andalusite, Kyanite and Sillimanite was studied in a batch system. Nano­-adsorbents were prepared via crushing, using a planetary ball mill and then characterized by different analyses such as: SEM, XRD, XRF and FT-IR. Major factors affecting the adsorption process were studied including pH, adsorbents dosage, initial metal concentration and temperature. Afterward, the adsorption process was studied isothermally, kinetically, and thermodynamically. The results show that aluminum silicates polymorphs are efficient adsorbents for removal of lead(II) and the removal exceeds 90%. The Freundlich isotherm model was best fitted with the experimental data. Chemisorption may control the rate of adsorption due to following the pseudo-second-order kinetic model. Thermodynamic investigation proved low randomness, exothermic and spontaneous nature of the process.

مجموعه گرانیتوئیدی کلاه قاضی در جنوب اصفهان و در پهنه ساختاری سنندج‌- سیرجان واقع شده است. بر اساس شواهد زمین‌شناسی سن احتمالی این مجموعه ژوراسیک بالایی بوده و شامل گروه های سنگی گرانودیوریت، گرانیت و آلکالی فلدسپار گرانیت است. کانی های اصلی تشکیل‌دهنده این مجموعه شامل کوارتز، پلاژیوکلاز و فلدسپار آلکالن بوده و بیوتیت تنها کانی فرومنیزین این مجموعه نفوذی است. حضور کانی های آندالوزیت، سیلیمانیت و گارنت در این مجموعه گرانیتوئیدی نشان‌دهنده منشأ رسوبی توده های مورد بررسی است. بر اساس مطالعات صحرایی، پتروگرافی و ژئوشیمیایی، سنگ‌های مجموعه نفوذی مورد بررسی در گروه گرانیتوئیدهای نوع S قرار می گیرند و دارای ماهیت کالک‌آلکالن پتاسیم بالا و از نوع پرآلومین هستند. از لحاظ ژئوشیمیایی طیف تغییرات SiO2 در نمونه های آنالیزشده از 6/64 تا 4/74 متغیر است. الگوی تغییرات عناصر کمیاب بهنجار شده نسبت به گوشته اولیه و کندریت بیانگر غنی‌شدگی این سنگ‌ها از LILE و LREE و تهی شدگی از HFSE و HREE است. نسبت 85/0-28/0 Eu/Eu*= در نمونه های کلاه قاضی نشان‌دهنده حضور اندکی پلاژیوکلاز در باقی‌مانده ذوب در منبع است. بر اساس شواهد زمین‌شناسی، کانی شناسی و ژئوشیمیایی مجموعه نفوذی کلاه قاضی در ژوراسیک بالایی و در طی نفوذ مذاب‌های گوشته ای به داخل پوسته و ذوب‌بخشی سنگ‌های پوسته ای تشکیل شده است.

L'objectif de cet article est de proposer une nouvelle methode d'estimation de teneur minerale qui associe deux techniques : l'analyse d'images et la geostatistique. Appliquee a la carriere d'andalousite de Glomel (France), cette methode comprend deux etapes essentielles. Tout d'abord, une mise au point du mode d'echantillonnage et de mesure permet une evaluation de la densite surfacique en andalousite sur une image de front de taille, et ce avec une erreur faible. Ensuite, les techniques de la geostatistique permettent de passer d'une evaluation sur une image a une estimation sur un volume de tir de mine, et ce avec une erreur d'estimation qui sera a calculer.

The PALMEIROPOLIS Cu-Zn (Pb) volcanogenic massive sulfide deposit, Brazil, consists of three ore bodies enclosed by hydrothermal alteration zones. The ore bodies and the alteration zones were metamorphosed under amphibolite fades conditions. The Palmeirdpolis alteration zones are characterized by a great diversity of bulk rock composition that originated a wide variety of low variance mineral assemblages. These assemblages are composed of orthoamphiboles (anthophyllite and gedrite), hornblende, biotite, garnet, staurolite, sillimanite, gahnite and, rarer, cordierite. Based on analyses of mineral chemistry aad mineral assemblages, temperatures are estimated to have been 550 - 625°C and pressures 2 - 5.5 kbar. The temperature of metamorphism that prevailed at the Palmeirdpolis deposit is comparable to other amphibolite fades massive sulfide deposits, such as Geco and Linda, Canada; Falun, Sweden; and Bleikvassli, Norway. The mineralogy of the alteration zones is similar in all these deposits even though they were metamorphosed at different pressure conditions, reflected by the crystallization of one of Al2 SiO5 phase (andalusite, sillimanite or kyanite).

Hydrothermal andalusite and corundum in the Elkhorn District, Montana

Topaz and Andalusite Mining in Brazil

EPR spectra of Fe3+ in andalusite and kyanite (both having formula Al2SiO5) are remeasured at bands which included 60 GHz. Results, besides the unusually large b and other spin-Hamiltonian parameters, include also the (true) g-factors. The spectra due to Fe3+Fe3+ pairs are identified in andalusite and analysed. EPR-Spektren von Fe3+ in Andalusit and Kyanit (beide mit der Formel Al2SiO5) werden erneut bei Frequenzen gemessen, die 60 GHz einschliesen. Als Ergebnis werden, neben dem ungewohnlich grosen b-Wert und anderen Spin-Hamiltonparametern, die (wahren) g-Faktoren erhalten. Durch Fe3+Fe3+-Paare hervorgerufene Spektren werden in Andalusit identifiziert und analysiert.

The paper describes the results obtained from the x-ray K-band spectra of Al for andalusite, sillimanite and kyanite. The fine structure of the aluminium K-band is correlated with the crystal structure of these minerals. It is considered that the difference between the energies of the K-and .KTjS'-lines depends on the distance between the aluminium and oxygen atoms. The energy differences between the Al and O atoms in andalusite, sillimanite and kyanite have been determined. The energy differences show a linear correlation to the known interatomic distances.

Andalusite and cordierite in some hornfelses from the vicinity of Matsumae, southwestern Hokkaidô

Andalusite in India

Andalusite in India

Andalusite in California and kyanite in North Carolina

An account is given of the development of andalusite for refractory purposes with descriptions of some uses to which it has been put.

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