Titanium in Muscovite, Biotite, and Hornblende: Modeling, Thermometry, and Rutile Activities of Metapelites and Amphibolites

Reactions involving the VITiIVAl-VIAlIVSi exchange in muscovite, biotite, and hornblende were calibrated thermodynamically using a set of experimental and natural data in rutile-plus quartz/coesite-bearing assemblages. The specific respective reactions are K(Al2)(AlSi3)O10(OH)2 + TiO2 = K(AlTi)(Al2Si2)O10(OH)2 + SiO2 (R1) K(□MgAl)Si4O10(OH)2 + TiO2 = K(□MgTi)AlSi3O10(OH)2 + SiO2 (R2) Ca2Mg3Al2Al2Si6O22(OH)2 + 2TiO2 = Ca2Mg3Ti2Al4Si4O22(OH)2 + 2SiO2. (R3) Ideal mixing on octahedral or octahedral plus tetrahedral sites and a non-ideal van Laar solution model yield the best regression results for thermodynamic fit parameters, with R2 values of 0.98–1.00. Isopleths of the equilibrium constant (Keq) show minimal pressure dependencies of \u3c1 \u3e°C/kbar, implying that the equilibria are poor barometers. Model reproducibility of the ideal portion of the equilibrium constant (Kid) is excellent (ca. ±0.1 to 0.3, 2σ), but the absolute value of the combined term ΔS+Kid is quite small (absolute values from 0 to 4), so calibration residuals propagate to temperature errors \u3e±50–100 °C, 1σ. Whereas the consistency of a mica or hornblende composition with a known T can be evaluated precisely, Ti chemistry in these reactions is sensitive to composition and does not resolve T (or P) well. The activity of TiO2 in rutile [a(rt)] was also evaluated using both the garnet-rutile-ilmenite-plagioclase-quartz (GRIPS) equilibrium and our new calibrations in rutile-absent, ilmenite-bearing rocks whose peak P-T conditions are otherwise known. Metapelites have average a(rt) of 0.9 (GRIPS) and 0.8 (R1), whereas amphibolites have a(rt) of 0.95 (GRIPS and R3). A value for a(rt) of 0.80 ± 0.20 (metapelites) and 0.95 +0.05/−0.25 (amphibolites) is recommended for trace-element thermomobarometers in ilmenite-bearing, rutile-absent rocks. The dependence of Ti contents of minerals on a(rt) and the reequilibration of Ti during metamorphic reactions both deserve further exploration, and may affect application of trace-element thermobarometers

The Mineralogy, Geochemistry and Phosphate Paragenesis of the Palermo #2 Pegmatite, North Groton, New Hampshire

An investigation of the beryl-phosphate subtype Palermo #2 pegmatite, located in the Grafton pegmatite field of New Hampshire, has revealed a large number of phosphate species. Late-stage, carbonate-bearing aqueous fluids have metasomatically altered primary phosphates producing a suite of nearly forty species of secondary phosphates. The secondary phosphates at Palermo #2 are a result of alteration of primary phosphates and associated silicate, carbonate, sulfide, arsenide and oxide minerals locally present in the core margin. Concomitant alteration of these associated minerals contributes the necessary ions to the hydrothermal fluids responsible for the formation of the diverse suite of secondary phosphates. Alteration of the mineral assemblage occurring in a given area creates a collection of secondary phosphates characteristic of that specific assemblage, whereas a completely different collection of secondary phosphates may appear only a few centimeters away. Thus, each suite of secondary phosphates is the product of its specific microenvironment of alteration

The Mineralogy, Geochemistry and Phosphate Paragenesis of the Palermo #2 Pegmatite, North Groton, New Hampshire

An investigation of the beryl-phosphate subtype Palermo #2 pegmatite, located in the Grafton pegmatite field of New Hampshire, has revealed a large number of phosphate species. Late-stage, carbonate-bearing aqueous fluids have metasomatically altered primary phosphates producing a suite of nearly forty species of secondary phosphates. The secondary phosphates at Palermo #2 are a result of alteration of primary phosphates and associated silicate, carbonate, sulfide, arsenide and oxide minerals locally present in the core margin. Concomitant alteration of these associated minerals contributes the necessary ions to the hydrothermal fluids responsible for the formation of the diverse suite of secondary phosphates. Alteration of the mineral assemblage occurring in a given area creates a collection of secondary phosphates characteristic of that specific assemblage, whereas a completely different collection of secondary phosphates may appear only a few centimeters away. Thus, each suite of secondary phosphates is the product of its specific microenvironment of alteration

New Mineral Names,

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Geochemical characteristics and structural setting of lithium–caesium–tantalum pegmatites of the Dorchap Dyke Swarm, northeast Victoria, Australia

The Dorchap Dyke Swarm hosts the first recorded occurrence of lithium–caesium–tantalum (LCT) pegmatites in Victoria, Australia. Syn-orogenic emplacement of pegmatite dykes occurred along a northwest-trending shear system during the Benambran Orogeny. Pegmatites are derived from fractionated melt associated with the Mount Wills Granite, which is an S-type, peraluminous granite originating from supracrustal melting of Ordovician sedimentary sequences. A distinct, eastward-oriented fractionation trend across the Dorchap Dyke Swarm has highlighted a 20 × 8 km highly fractionated zone in the northeastern Dorchap Range, which includes spodumene- and petalite-bearing pegmatites. A distinct pattern of elemental enrichment (P > Cs > Be > N

Microscopical Methods for the In Situ Investigation of Biodegradation on Cultural Heritage

The processes of cultural heritage sites’ degradation reveal interactions between the chemical characteristics of the substrates, the underlying substrate penetration, and the microbiota systems. Microorganisms penetrate the stone, causing extensive disaggregation of the materials. This chapter reveals comparative studies between the usual research approaches applied in biodegradation studies, especially optical microscopy, epifluorescence, and electron microscopy (SEM). These in situ microscopy techniques propose some complex analyses for the evaluation of the relationship between the microorganism’s cells and the stone surfaces (adherence, interactions), and also for the evaluation of the level of health or balance of the niche complex, from mesoscale to microscale. The stages of the exact monitorization and evaluation of lithotypes and deterioration phenomena are periodical sampling and monument mapping. The aim of this chapter is to identify microscopical methods used in biodegradation studies, especially the facilities provided by these methods. Our in situ analysis (light microscopy, epifluorescence, and scanning electron microscopy) performed for the first time on the painted Matia-Fresco Loggia (Corvin Castle, Romania) highlighted several aspects, such as mixtures of mineral elements with different chromatic appearance and porosity, shredding degradation, depigmented areas, cracked portions, and highly biota activity (bacterial and fungal) on painted surface

Classifying minerals and their related names in a relational database

AbstractThe categorisation of minerals and their related names, such as synonyms, obsolete or historical names, varieties or mixtures, is an asset for designing an interoperable and consistent mineralogical data warehouse. An enormous amount of this data, provided by mindat.org and other resources, was reviewed and analysed during the research. The analysis indicates the existence of several categories of (1) the abstract titles or designations representing the link to the original material or a group of names or substances without actual physical representation, and (2) the unique names representing actual physical material, compounds, or an aggregate of one or more minerals. A revision of the dependency between the categories attributes stored in a database (e.g. chemical properties, physical properties) and their classification status assigned allowed us to design a robust prototype for maintaining database integrity and consistency. The proposed scheme allows standardisation and structuring of officially regulated and maintained species, e.g. IMA-approved, and, in addition, unregulated ones.Abstract The categorisation of minerals and their related names, such as synonyms, obsolete or historical names, varieties or mixtures, is an asset for designing an interoperable and consistent mineralogical data warehouse. An enormous amount of this data, provided by mindat.org and other resources, was reviewed and analysed during the research. The analysis indicates the existence of several categories of (1) the abstract titles or designations representing the link to the original material or a group of names or substances without actual physical representation, and (2) the unique names representing actual physical material, compounds, or an aggregate of one or more minerals. A revision of the dependency between the categories attributes stored in a database (e.g. chemical properties, physical properties) and their classification status assigned allowed us to design a robust prototype for maintaining database integrity and consistency. The proposed scheme allows standardisation and structuring of officially regulated and maintained species, e.g. IMA-approved, and, in addition, unregulated ones

Mineralogy and Geochemistry of the Dumper Dew Pegmatite, Oxford County, Maine

The Dumper Dew is a newly discovered pegmatite located on the eastfacing slope of Uncle Tom Mountain in Oxford County, Maine. It is a geochemically evolved LCT-type pegmatite petrogenetically linked to the middle Paleozoic Sebago batholith. Shallow emplacement of the Dumper Dew is evidenced by abundant miarolitic cavities found in the pegmatite. The sheet-like structure of the pegmatite coupled with its intrusion in lowmetamorphic grade country rock suggests rapid crystallization. Northern portions of the wall zone and intermediate zones have undergone hydrothermal alteration by the migration of late-stage fluids. The pegmatite hosts a diverse assemblage of rare-element mineral phases due to its high degree of geochemical fractionation. Trends of geochemical fractionation of individual mineral phases such as K-feldspar, muscovite, garnet, apatite, beryl, spodumene, triphylite-lithiophilite, tourmaline, cassiterite, and columbite-tantalite were attained via instrumentation assay. These trends illustrate an enhanced degree of magmatic differentiation relative to other pegmatites in the area