Peter W. Scott

Acid activation and bleaching capacity of bentonites from the islands of Milos and Chios, Aegean, Greece

Acid activation with HCl of two bentonites from the Aegean Islands of Milos and Chios, Greece, consisting of Chambers and Tatatilla-type and Otay-type montmorillonite, respectively, resulted in a 4 to 5-fold increase of the surface area of the raw materials. The activated materials have been rendered suitable for decolorization (bleaching) of rapeseed oil through removal of β-carotene. The optimum bleaching capacity is not associated with maximum surface area. Activation is characterized by destruction of the original smectite structure, removal of octahedral cations, uptake of OH− and formation of au amorphous Si-rich phase. Mg is the most readily removed element affecting the tendency for activation. The Otay-type montmorillonites are activated. more easily. Optimum conditions for activation are obtained using a variety of combinations of acid strength and residence time. The combination which is likely to be preferred on an industrial scale, is the least energy consuming. Therefore shorter treatments with more dilute acid are preferable.

Blueschist-Greenschist Transition in the Mt. Hibernia Schist, Union Hill, Parish of St. Thomas, Jamaica

The Mt. Hibernia Schist occurs in fault-bounded blocks on the southwestern side of the Blue Mountain Inlier in eastern Jamaica. The metamorphosed sediments and volcanic rocks are part of an Early Cretaceous accretionary complex. The metamorphism reflects a Sanbagawa facies series, wherein two facies, blueschist and greenschist, and transitional schist are recognized. The typical assemblages are: blueschist: Gln + Pmp + [Epi] + Act + Chl + Qtz + Alb + Cpx; transitional: Gln + Pmp + Epi + Act + Chl + Qtz + Alb + Cpx; greenschist: Epi + Act + Chl + Qtz + Alb + Cpx, where only traces of epidote (square brackets) occur in the blueschist assemblage. The clinopyroxene is relict in all assemblages. P-T conditions for the blueschist and transitional schist were estimated by multiple equilibria analysis involving mineral components in NCMASH. Estimated P-T conditions for the blueschist are 5.1-6.2 kbars and 290-366°C. Estimated P-T conditions for the transitional schist are 2.6-3.5 kbar and 235-240°C. Textural relationships indicate a retrograde paragenesis (blueschist to greenschist), which can be summarized by a reaction of the general form: Gln + Pmp + Cpx + Qtz = Act + Epi + Chl + Alb (1). Details of the transition are explained by three NCMASH+Fe2O3 equilibria, here generalized: Gln + Epi + Qtz + H2O = Act + Chl + Alb (2); Pmp = Epi + H2O (3); and Gln + Pmp + Qtz = Act + Epi + Chl + Alb + H2O (4). The highest P-T conditions are represented by the blueschist assemblage, Gln + Pmp + Act + Chl + Qtz + Alb + (relict Cpx). Upon decompression and cooling, conditions meet reaction (4). The equilibrium accounts for the transitional assemblage, Gln + Pmp + Epi + Act + Chl + Qtz + Alb + (Cpx), marked by the presence of epidote. Viewed as a reaction, equilibrium (4) ceases when either the glaucophane or the pumpellyite is used up, resulting in two possible assemblages—Act + Epi + Pmp + Chl + Alb + Qtz or Gln + Act + Epi + Chl + Alb + Qtz—neither of which is the greenschist assemblage. The final greenschist assemblage comes about as the result of the elimination of any remaining glaucophane or pumpelleyite by reactions (2) and (3), respectively. We propose a two-stage retrograde P-T-time path, involving (1) prolonged residence at a particular depth, consistent with a pressure of about 5 kbar for the transitional schist, followed by (2) rapid uplift and exhumation.

Petrology and Inferred Tectonic Setting of the Mountain Pine Ridge Granitoids, Maya Mountains, Belize

The Mountain Pine Ridge batholith is the largest of three major granitoid intrusions that crop out in the Maya Mountains of Belize. These plutons intrude a thick sequence of Upper Paleozoic metasedimentary and metavolcanic rocks known as the Santa Rosa Group. The mineralogy of the granitic rocks at Mountain Pine Ridge varies and the rocks are classified into four petrographic types—biotite leucogranite, muscovite leucogranite, granodiorite, and tonalite. The essential felsic minerals in these rocks include quartz, microcline, plagioclase feldspar ± perthite, and muscovite, whereas the only mafic mineral is biotite. Microprobe analysis shows that significant differences exist between the biotites of the different petrographic types, especially in the levels of Al(vi), Mn, Mg, total Fe, and the Fe/Fe+Mg ratio. Major, minor and trace-element chemistry of the four petrographic types indicates that the Mountain Pine Ridge batholith is composed of three different suites of granitic rocks. Although all three sui...

The volcaniclastic turbidites of the Grand Bay Formation, Carriacou, Grenadines, Lesser Antilles

Abstract. The Middle Miocene Grand Bay Formation is exposed on the eastern half of the island of Carriacou, Grenada Grenadines. The formation was deposited in water depths of greater than 150 m and is mainly composed of a sequence of bioclastic and volcanogenic turbidites. The dominant rock type in the Grand Bay Formation is fine- to coarse-grained sandstones. The volcaniclastic sandstones are poorly sorted and immature, and contain volcanic clasts, clinopyroxene, amphibole, plagioclase feldspar and opaque crystals in an argillaceous matrix. Within the Grand Bay Formation are beds of subaequeous lapilli and ash tuff representing pyroclastic fall deposits that have a mineralogy that is similar to the heavy minerals in the turbidites. The mineral assemblage of the lapilli tuffs suggests that these eruptions were basaltic andesite or andesite in composition. It is postulated that the volcanogenic turbidites in the Grand Bay Formation formed as a consequence of volcanic eruptions along the southern Lesser Antilles arc during the Early to Middle Miocene. The lithic volcanic fragments and mineral composition of the volcaniclastic turbidites indicate a monomagmatic source in which reworked pyroclastic deposits were temporarily stored on a shallow shelf prior to deposition downslope, in a deep water basin.

THE SERPENTINIZATION OF PERIDOTITE FROM CEDAR VALLEY, JAMAICA

Previously undescribed, microscopic textures in partially serpentinized peridotite shed light on the process of serpentinization. Fracturing and fragmentation of the peridotite protolith produced a modest increase in volume and opened channels to reactive aqueous fluids. Prior to, or in conjunction with, the first appearance of serpentine, micrometer-scale grains of magnetite crystallized on the surfaces of fractures. This decoration of fracture surfaces faithfully preserved the original, angular outlines of fragments of forsterite and pyroxene through all stages of serpentinization. Simple geometric considerations indicate that the volume of a given fragment did not change during replacement. Partially serpentinized forsterite shows a penetrative, micrometer-scale, sieve or sponge texture. Fifty percent or more of the volume of optically continuous forsterite can consist of micrometer-scale perforations, filled with serpentine. This sponge texture has not been described elsewhere. The delicate connection...

Markets for industrial mineral products from mining waste

Abstract The composition of mining waste varies according to the nature of the mining operation and many other factors, but where the same mineral is extracted from a similar style of metalliferous or industrial mineral deposit or coal, the waste usually has similar characteristics. There are many potential sources of industrial minerals from mining waste. Waste from one mine may be a byproduct or coproduct in a mining operation elsewhere. Much technical research work on mine waste utilization, for example studies on slate waste, has included a manufacturing process. The waste is invariably an inferior material compared with an industrial mineral from a primary resource for the manufacturing process. Successful markets have not been found. Four scenarios are proposed where an industrial mineral product made from mining waste may be marketed successfully. These are a bulk product for a local market made with minimal or no processing; a low unit value product and a cost-effective alternative source of a mineral for local industry; an industrial mineral commodity traded nationally or internationally; and extraction of a high unit value rare mineral. Making an industrial mineral product from mining waste and successfully marketing it should involve minimal processing of the waste consistent with the value of the mineral product.

The climate for development of Albania's mineral resources

Abstract Prior to 1991 mineral commodities generated the main contribution to Albanias foreign-exchange earnings, but political upheaval marked the end for the state mining enterprises. The deposits of bauxite, chromite, copper, nickel and industrial and construction materials now offer opportunities for revival of the countrys solid minerals industry with Western participation. The legislative framework for this was established by laws passed in 1991 and 1994, but attitudes inherited from the Communist regime need to change further to facilitate the entry of foreign developers.

Sustainable river mining of aggregates in developing countries

Abstract Throughout the developing world, river sand and gravel is widely exploited as aggregate for construction. Sediment is often mined directly from the river channel and makes an important contribution to the national demand for aggregates. However, instream mining, if not carefully controlled, can cause significant damage to the river and its associated biota, and to the adjacent land, as well as creating conflict with other users of the river. The economic and environmental geology of river sand and gravel mining in developing countries is poorly known and there is little knowledge available to inform existing regulatory strategies. Research work on selected river systems in Jamaica and Costa Rica has generated a considerable amount of new information on resources and sediment budgets, on market and supply options, on the physical, biological and social impacts of extraction, and on best-practice legislative and mineral planning issues. A methodology has been developed for effective control of instream sand and gravel mining operations including a Code of Practice, which regulators can use for examining and reconciling the conflicting claims of sand and gravel extraction and the environment.

ISO 9000 quality assurance certification in the mining sector of Greece

All over the world, businesses have started moving towards Quality Assurance and the adoption of ISO 9000 Standards. In this study, we examined the status of the Quality Assurance Certification of companies which operate in the mining sector in Greece. It is certain that the companies have started working towards Quality Management and Quality Assurance Certification. The movement towards Quality Assurance is customer driven. The specific motives for implementing Quality Assurance Certification were customer satisfaction, to gain a competitive advantage and improve business efficiency. They anticipate a better business image, to increase customer satisfaction and strengthen their market share. The level of criticism for some aspects of the ISO 9000 certification, which has been recorded in other parts of the world, was not found in Greece. Following the introduction of ISO 9000, some mining companies also included in their strategy the introduction of ISO 14000 which relates to Environmental Management Systems.