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ELIAS, 1988. Petrology and structure of the early Proterozoic Pirilä gold deposit in southeastern Finland. Bull. Geol. Soc. Finland 60, Part 1,[55][56][57][58][59][60][61][62][63][64][65][66] The Pirilä gold deposit is located in the southeastern part of the Ladoga-Botnian Bay Zone, in a volcano-sedimentary environment metamorphosed under PT conditions of the amphibolite facies. Metavolcanic rocks include felsic and intermediate pyroclastics and tholeiitic to komatiitic lavas. The stratigraphically underlying metasedimentary rocks are mainly graywackes with some limestone and calc-silicate rocks.Sulfide and gold bearing quartz veins and lenses occur in a transitional zone between volcanic and sedimentary units, the latter including a narrow iron formation of silicate, oxide, and sulfide facies. The quartz veins and lenses were emplaced during the F : and F 3 deformational phases.The most common ore minerals are arsenopyrite, löllingite, pyrrhotite, and pyrite. In some places there is also abundant galena, sphalerite, and chalcopyrite. Gold and sulfides are associated with either quartz lenses and veins or with quartzcummingtonite rock. The gold occurs predominantly as inclusions in arsenopyrite or in löllingite, and is only rarely visible macroscopically. The grains are mostly electrum, the silver content of the analyzed grains ranging between 10.6 and 60.0 percent. Silver also occurs as small dyscrasite inclusions in galena.The in situ ore reserves of the Pirilä deposit are 150,000 t at 8 g/t gold and 30 g/t silver. Smaller gold occurrences in a similar stratigraphic position are found near the Pirilä deposit. Further indications of gold are met along the same stratigraphic horizon over a distance of at least 30 kilometers.

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The utilization of biomass fly ash and lime was investigated as cement replacements in blast furnace briquetting. Sample characterization included chemical (XRF) and mineralogical (XRD) analysis, particle size determination, and thermal behaviour (TGA/DSC-TGA). Additionally, the mechanical performance and fly ash, lime, and fly ash/lime mixtures as cement replacements were determined by incorporation in mortars tested by standardized methods (EN 196-1). Based on the results, detrimental alkali, sulphur, and chlorine contents of the biomass fly ashes do not seem to restrict use in briquetting. However, the utilization of fly ashes as cement replacements resulted in significant decline of 28 day compression strength values. The two different fly ash samples attested to 28 day compression strength of app. 72% and 55% of the respective control. Inferior mechanical performance was related to moisture absorption according to XRD and DSC-TGA and relatively larger particle size. Respectively, lime additions encouraged fly ash strength development only in the case of inferior fly ash performance related to the aforementioned effects. The results provide important information for the forthcoming manufacture of blast furnace test briquettes, which is to commence in the near future.