Biotite, the dominant ferromagnesian mineral in Paleozoic granitic rocks of the Canadian Appalachians, has been analyzed with an electron microprobe (wavelength dispersion) for major elements and by 57 Fe Mössbauer spectroscopy. We sampled a wide variety of rock types, ranging from gabbro, diorite, syenite to granite, but by far mostly granitic (sensu lato). The most pronounced variations are in total Al contents and Fe/(Fe + Mg) values. In the biotite quadrilateral (annite-siderophyllitephlogopite-eastonite), biotite from A-type granites of the Humber and Avalon zones in Gaspé (Québec) and New Brunswick is characterized by low mean Al contents, ~1.15 atoms per formula unit (apfu), and variable Fe/(Fe + Mg) values in the range 0.4 to 0.9. In the granites of the Notre Dame arc of the Dunnage zone in Newfoundland, biotite has moderate mean values of Al (~1.40 apfu) and Fe/(Fe + Mg) (~0.58). In granites of the Gander zone of New Brunswick and Newfoundland, biotite has a mean Fe/(Fe + Mg) value of 0.6 and shows a pronounced trend of increasing total Al (1.05 to 1.75 apfu), confirming significant contributions of aluminous supracrustal material to the magmas, either by assimilation or anatexis. Finally, in granites of the Meguma zone, derived entirely from metasedimentary material, biotite exhibits a remarkable increase in total Al (1.30 to 2.00 apfu) and considerable iron-enrichment [Fe/(Fe + Mg) in the range 0.4 to 1], with compositions nearing the siderophyllite endmember. The biotite from most zones plots on or above the NNO buffer, indicating moderately oxidizing conditions, whereas that from the Meguma zone plots mainly between the QFM and NNO buffers, implying fairly reducing conditions during crystallization. Assuming a reasonable range of crystallization temperatures of 750 to 900°C, oxygen fugacities ranged from 10-10 to 10-16.9 bars during crystallization. The composition of biotite reflects primarily the nature of the host magmas. It cannot readily be used for tectonomagmatic characterization of these rocks without the aid of other types of data.

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Relative intensity of Cu and Ni K lines in the x‐ray spectrum of brass plates coated with Ni of different thicknesses was measured by X‐Ray Fluorescence (XRF) spectrometry. The obtained results show that relative intensities, Kα/Kβ, of Cu and Ni K lines are increasing functions of Ni layer thickness. Thereby, these relative intensities can be used to measure the thickness of Ni layer on brass plate in the range of fractions of one to several micrometers. This method can also be used to measure the thickness of other coating materials. Copyright © 2009 John Wiley & Sons, Ltd.

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