Milton Luiz Laquintinie Formoso

SUMMARY OF RECOMMENDATIONS OF NOMENCLATURE COMMITTEES RELEVANT TO CLAY MINERALOGY: REPORT OF THE ASSOCIATION INTERNATIONALE POUR L'ETUDE DES ARGILES (AIPEA) NOMENCLATURE COMMITTEE FOR 2006

Brindley et al. (1951) reported the earliest efforts to obtain international collaboration on nomenclature and classification of clay minerals, initiated at the International Soil Congress in Amsterdam in 1950. Since then, national clay groups were formed, and they proposed various changes in nomenclature at group meetings of the International Clay Conferences. Most of the national clay groups have representation on the Nomenclature Committee of the Association Internationale pour l’Etude des Argiles (AIPEA, International Association for the Study of Clays), which was established in 1966. The precursor committee to the AIPEA Nomenclature Committee was the Nomenclature Subcommittee of the Comite International pour l’Etude des Argiles (CIPEA, International Committee for the Study of Clays). The AIPEA Nomenclature Committee has worked closely with other international groups, including the Commission on New Minerals and Mineral Names (CNMMN) of the International Mineralogical Association (IMA), which is responsible for the formal recognition of new minerals and mineral names, and the International Union of Crystallography (IUCr), which considered extensions to the nomenclature of disordered, modulated and polytype structures (Guinier et al. , 1984) published earlier by a joint committee with the IMA (Bailey, 1977). In contrast to the other national clay groups, however, The Clay Minerals Society (CMS) Nomenclature Committee, which was established in 1963 at the same time as the CMS and predates the AIPEA Nomenclature Committee, remains in existence and occasionally produces recommendations. The precursor to this committee was the Nomenclature SubCommittee, which was organized in 1961 by the (US) National Research Council. The Chair of the AIPEA Nomenclature Committee is a standing member of the CMS Nomenclature Committee so that the committees are in close contact. The purpose of the AIPEA Nomenclature Committee has been to make general and specific recommendations concerning: (1) definitions of mineralogical and crystallographic clay-related terms; (2) classification and terminology …

REPORT OF THE ASSOCIATION INTERNATIONALE POUR L’ÉTUDE DES ARGILES (AIPEA) NOMENCLATURE COMMITTEE FOR 2001: ORDER, DISORDER AND CRYSTALLINITY IN PHYLLOSILICATES AND THE USE OF THE “CRYSTALLINITY INDEX”

The purpose of this report is to describe the appropriate use of indices relating to crystallinity, such as the ‘crystallinity index’, the ‘Hinckley index’, the ‘Kubler index’, and the ‘Arkai index’. A ‘crystalline’ solid is defined as a solid consisting of atoms, ions or molecules packed together in a periodic arrangement. A ‘crystallinity index’ is purported to be a measure of crystallinity, although there is uncertainty about what this means (see below). This report discusses briefly the nature of order, disorder and crystallinity in phyllo-silicates and discusses why the use of a ‘crystallinity index’ should be avoided. If possible, it is suggested that indices be referred to using the name of the author who originally described the parameter, e.g. ‘Hinckley index’ or ‘Kubler index’, or in honor of a researcher who investigated the importance of the parameter extensively, e.g. ‘Arkai index’. In contrast to a crystalline solid, an ‘amorphous’ solid is one in which the constituent components are arranged randomly. However, many variations occur between the two extremes of crystalline vs. amorphous. For example, one type of amorphous material might consist simply of atoms showing no order and no periodicity. Alternatively, another amorphous material may consist of atoms arranged, for example, as groups of tetrahedra ( i.e. limited order) with each group displaced or rotated ( e.g. without periodicity) relative to another. Thus, this latter material is nearly entirely amorphous, but differs from the first. Likewise, disturbance of order and periodicity may occur in crystalline materials. The terms ‘order’ and ‘disorder’ refer to the collective nature or degree of such disturbances. Although seemingly simple notions, ‘crystalline’ and ‘amorphous’ are complex concepts. Crystalline substances may show a periodic internal structure based on direction. For example, two-dimensional periodicity is common in phyllosilicates where two adjacent sheets or layers must mesh. For example, in serpentine, …

Report of the Association Internationale pour l’Etude des Argiles (AIPEA) Nomenclature Committee for 2001: Order, disorder and crystallinity in phyllosilicates and the use of the ‘Crystallinity Index’

The purpose of this report is to describe the appropriate use of indices relating to crystallinity, such as the ‘crystallinity index’, the ‘Hinckley index’, the ‘Kubler index’, and the ‘Arkai index’. A ‘crystalline’ solid is defined as a solid consisting of atoms, ions, or molecules packed together in a periodic arrangement. A ‘crystallinity index’ is purported to be a measure of crystallinity, although there is uncertainty about what this means (see below). This report discusses briefly the nature of order, disorder and crystallinity in phyllosilicates and discusses why the use of a ‘crystallinity index’ should be avoided. If possible, it is suggested that indices be referred to using the name of the author who originally described the parameter, as in ‘Hinckley index’ or ‘Kubler index’, or in honour of a researcher who investigated the importance of the parameter extensively, as in ‘Arkai index’. In contrast to a crystalline solid, an ‘amorphous’ solid is one in which the constituent components are arranged randomly. However, many variations occur between the two extremes of crystalline vs. amorphous. For example, one type of amorphous material might consist simply of atoms showing no order and no periodicity. Alternatively, another amorphous material may consist of atoms arranged, for example, as groups of tetrahedra (i.e. limited order) with each group displaced or rotated (e.g. without periodicity) relative to another. Thus, this latter material is nearly entirely amorphous, but differs from the first. Likewise, disturbance of order and periodicity may occur in crystalline materials. The terms ‘order’ and ‘disorder’ refer to the collective nature or degree of such disturbances. Although seemingly simple notions, ‘crystalline’ and ‘amorphous’ are complex concepts. Crystalline substances may show a periodic internal structure based on direction. For example, two-dimensional periodicity is common in phyllosilicates where two adjacent sheets or layers must mesh. For example, …

Summary of recommendations of nomenclature committees relevant to clay mineralogy: report of the Association Internationale pour l’Etude des Argiles (AIPEA) Nomenclature Committee for 2006

Brindley et al. (1951) reported the earliest efforts to obtain international collaboration on nomenclature and classification of clay minerals, initiated at the International Soil Congress in Amsterdam in 1950. Since then, national clay groups were formed, and they proposed various changes in nomenclature at group meetings of the International Clay Conferences. Most of the national clay groups have representation on the Nomenclature Committee of the Association Internationale pour l’Etude des Argiles (AIPEA, International Association for the Study of Clays), which was established in 1966. The precursor committee to the AIPEA Nomenclature Committee was the Nomenclature Subcommittee of the Comite International pour l’Etude des Argiles (CIPEA, International Committee for the Study of Clays). The AIPEA Nomenclature Committee has worked closely with other international groups, including the Commission on New Minerals and Mineral Names (CNMMN) of the International Mineralogical Association (IMA), which is responsible for the formal recognition of new minerals and mineral names, and the International Union of Crystallography (IUCr), which considered extensions to the nomenclature of disordered, modulated and polytype structures (Guinier et al. , 1984) published earlier by a joint committee with the IMA (Bailey, 1977). In contrast to the other national clay groups, however, The Clay Minerals Society (CMS) Nomenclature Committee, which was established in 1963 at the same time as the CMS and predates the AIPEA Nomenclature Committee, remains in existence and occasionally produces recommendations. The precursor to this committee was the Nomenclature Sub-Committee, which was organized in 1961 by the (US) National Research Council. The Chair of the AIPEA Nomenclature Committee is a standing member of the CMS Nomenclature Committee so that the committees are in close contact. The purpose of the AIPEA Nomenclature Committee has been to make general and specific recommendations concerning: (1) definitions of mineralogical and crystallographic clay-related terms; (2) classification and terminology …

Heavy metals in stream sediments from copper and gold mining areas in southern Brazil

Abstract This work is part of a research effort which is intended to identify natural and anthropogenic sources for metal contamination in gold and copper mining areas of the Camaqua River Basin, located in the shield region of the Rio Grande do Sul state. This particular study area is located in the upper Camaqua River Basin, where gold, copper and marble occurs. Stream bed sediments were collected during four sampling periods, between 1992 and 1994. Total Fe, Mn, Cu, Zn, Pb and Hg concentrations as well as TOC contents were determined in the silt-clay fraction of all collected samples. Sequential extractions were performed in some selected samples to evaluate geochemical phase associations and potential metal mobilities. A general increase in metal concentrations was observed in more recent sampling periods for Mn, Fe and Cu, especially in the copper mining area. Two groups of metals, Cu-Fe and Hg-Pb-Zn-Mn, presented some similarities in spatial distributions, but exhibited different geochemic behaviors in the gold and copper mining areas.

Alteration processes of a thick basaltic lava flow of the Paraná Basin (Brazil): petrographic and mineralogical studies

Abstract Petrographic and mineralogical studies of a 45 m thick basaltic lava flow in southern Parana Basin (Rio Grande do Sul, Brazil) enables a detailed description of three structural levels: the lower vesicular zone (LVZ), inner massive zone (IMZ), and upper vesicular zone (UVZ). The three levels, inherited from cooling stages, are characterized by vertical zonation of the petrographic features and associated secondary mineral assemblages, such as clay minerals and zeolites. Zeolite crystallization is limited to the vesicle infilling and partial replacement of albitized plagioclases. The clay mineral sequence observed in vesicle infilling is a celadonite, saponite, chlorite/saponite mixed layer. The mesostasis of the three levels, which constitutes reduced sites of clay mineral crystallization from the peripheral levels (top and base) to the inner, massive, and vesicle-free part of the flow, presents a saponite to C/S mixed layer sequence. Petrographic and chemical observations support three steps for the alteration mechanisms. The earliest alteration stages are related to postmagmatic mechanisms. They are marked by earliest celadonite precipitation in the oxidative condition of the highly permeable UVZ, saponite with homogeneous compositions in reducing conditions, and C/S mixed layer conversion in the inner part of the flow, where temperature gradients have been preserved during the final stages of cooling. The albitization of plagioclase associated with zeolite crystallization and the compositional changes in clay mineralogy should be attributed to high water/basalt alterations during the low-grade burial metamorphic conditions in more permeable vesicular levels of the flow.

The smectitic minerals in a bentonite deposit from Melo (Uruguay)

Abstract A nearly monomineralic 1.5 m thick bentonite bed sampled in Melo (Uruguay) appears to be a pure high-charge montmorillonite: [Si3.94Al0.06](Al1.40Fe3+0.11Ti0.02Mg0.49Mn0.01)O10(OH)2Na0.01K0.08Ca0.18. However, contrasting swelling behaviours have been demonstrated by fitting the experimental X-ray diffraction patterns which were recorded on oriented preparations of the same sample in different saturation states. According to the expandability of the layers in the Ca-, K- and K-Ca-saturated (i.e. saturated first with K+ and subsequently with Ca2+) states, three ‘layer types’ were defined. Low-, intermediate-, and high-charge layers are fully, partly, and not expandable, respectively, after K-saturation. Collapse of high-charge layers is not reversible after subsequent Ca-saturation, probably because of tetrahedral substitutions. These three different layer types are segregated in two distinct randomly interstratified mixed-layer phases. Total surface area and cation exchange capacity are shown to depend on the interlayer cation composition.

GENESIS, MINERALOGY AND GEOCHEMISTRY OF KAOLIN DEPOSITS OF THE JARI RIVER, AMAPÁ STATE, BRAZIL

Kaolin samples from the Jari deposit (Amazon region) were studied using various techniques to characterize its structural and crystallochemical aspects, and to establish its origin and evolution. A profile 60 m thick was selected in a kaolin mine (Morro do Felipe) located at the banks of the Jari river. Despite the great thickness of the deposit and the variety of kaolin types, the mineralogical composition is rather homogeneous and is mainly kaolinite associated with gibbsite and small amounts of quartz, anatase, goethite and hematite. The field observations and the morphological analysis indicate the existence of sedimentary features throughout the whole profile except for the upper aluminous clayey layer (Belterra Clay). This is evidence that the Rio Jari kaolin deposit originated from sedimentary material, the Alter do Chão Formation. The presence of alternating clay and sandy layers is explained by sedimentation processes with great depositional energy variation. Thus, the accumulation of thick clay layers was related to a low-energy phase, and during the high-energy phases, the deposition process led to the accumulation of sandy materials, constituted essentially of quartz and showing strong textural and structural variation. Later on, periods of hydromorphy were responsible for iron removal and consequently for the bleaching of the sedimentary formation. The crystallinity data show an increase of the structural disorder toward the surface associated with an increase in the amount of structural Fe in the kaolinite. The Rio Jari kaolin deposits should be considered as having originated from kaolinitic clay sediments of the Alter do Chão formation (protore) that was submitted to intensive lateritic weathering processes.

A bentonite bed in the Aceguá (RS, Brazil) and Melo (Uruguay) areas: a highly crystallized montmorillonite

Abstract Two occurrences of bentonite beds have been studied in Acegua (RS, Brazil) and Melo (Uruguay). Despite their different thicknesses, the two profiles seem to belong to the same bentonite bed because of their similar petrographical and mineralogical properties (color, density, composition). Both are composed of a nearly pure smectite mineral that is dominantly a montmorillonite. High amounts of Mg ions in the octahedral sheet elevate the layer charge approximately 0.5 per Si 4 O 10 . The layer charge is mostly compensated for by Ca 2+ ions in the interlayer. The rare earth element (REE) patterns are different from the post-Archean Australian average shale (PAAS) standard. In particular, when the data are PAAS normalized, the pattern obtained shows that the bentonite is LREE depleted. Thus, it cannot have originated from detrital sources. Despite diagenetic conditions that favor the crystallization of random illite/smectite mixed layers from detrital clays in the surrounding formations, the mineral reactions in the bentonite bed are limited to a few Al for Si substitutions in the tetrahedral sheets. The clays remain dominantly montmorillonite with abnormally high crystallinity.

Mercury in sediments from gold and copper exploitation areas in the Camaquã River Basin, Southern Brazil

Abstract Mercury concentrations were determined in stream sediments from the Camaqua River Basin, located in the shield region of the state of Rio Grande do Sul, southern Brazil. The resulting geochemical data show that overbank floodplain deposits exhibit higher concentrations than sediments collected from the active channel bed. In addition, higher Hg concentrations were measured in the fine(