Boron speciation in aqueous fluids at 22 to 600°C and 0.1 MPa to 2 GPa

Liquid-vapor fractionation of boron and boron isotopes: Experimental calibration at 400°C/23 MPa to 450°C/42 MPa

“…Isotopic fractionation is inversely correlated with temperature ranging from ⌬ 11 B fluid-mineral of 33‰ for fluid-clay at 25°C (Palmer et al, 1987) to about 6‰ for fluid-muscovite at 700°C (Wunder et al, 2005), and to a few ‰ for fluid-melt above 1000°C (Hervig et al, 2002). There is now overall agreement that the main fractionation effect is due to the change from trigonal boron in neutral pH hydrous fluids to tetrahedrally coordinated boron in most rock-forming minerals (see also Peacock and Hervig, 1999;Schmidt et al, 2005).…”

Boron isotope systematics of a fossil hydrothermal system from the Troodos ophiolite, Cyprus: Water–rock interactions in the oceanic crust and subseafloor ore deposits

“…Boron isotopic fractionation between fluids and minerals depends on temperature and on the proportions of different boron coordinations in the interacting fluid and mineral phases (Palmer and Swihart, 1996;Peacock and Hervig, 1999;Williams et al, 2001;Hervig et al, 2002;Wunder et al, 2005). Boron is predominantly 10 B-enriched and tetrahedrally coordinated in most silicate minerals, whereas 11 B-enriched trigonally coordinated boron predominates in the fluid phase (Palmer and Swihart, 1996;Schmidt et al, 2005). The temperature-dependent boron isotopic fractionation between mineral and fluid is approximated by the equation Δ 11 B mineral-fluid = −10.69 (1000 / T [K]) + 3.88, based on experimental studies (Wunder et al, 2005).…”

Hambergite-rich melt inclusions in morganite crystals from the Muiane pegmatite, Mozambique and some remarks on the paragenesis of hambergite

“…The main daughter mineral in inclusions in the Muiane morganite is hambergite The concentration of boron in the inclusions and water in the inclusion glass was estimated by Raman analysis according to Thomas (2002), Schmidt et al (2005), Thomas and Davidson (2006) and Thomas et al (2006).…”