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Solubility of hydroxyl in natural quartz annealed in water at 900°C and 1.5 GPa
Author(s) -
Rovetta Mark R.,
Holloway John R.,
Blacic James D.
Publication year - 1986
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl013i002p00145
Subject(s) - quartz , deuterium , analytical chemistry (journal) , impurity , annealing (glass) , hydrogen , hydrothermal circulation , materials science , mineralogy , infrared spectroscopy , oxide , chemistry , metallurgy , geology , environmental chemistry , physics , organic chemistry , quantum mechanics , seismology
We have measured the infrared spectra of a natural quartz after annealing it for up to 37 hours in water at 900°‐1000°C and 1.0‐1.5 GPa under chemical conditions buffered through a hydrogen membrane with an assemblage of water, nickel metal, and nickel oxide. From integral absorbances in the 3400 and 2500 cm −1 regions we calculated the concentration of hydrogen and deuterium present in the samples as hydroxyl. Concentrations reported in this work are calibrated to the deuterium content of a sample annealed 37 hours in D 2 O 18 as determined by nuclear reaction analysis. Hydrothermal annealing increased the hydroxyl content of natural quartz (A‐1) from 26 to 75 ± 11 H/10 6 Si. Absorption increased by growth of O‐H bands it 3318, 3483, and 3432 cm −1 associated with A1 3+ . Samples annealed in D 2 O 18 showed an increase in bands near 2500 cm −1 associated with O‐D and A1 3+ . An O‐H band in the starting material at 3485 cm −1 , associated with Li + , was absent from the spectra of annealed samples. Fractured samples were characterized by the appearance of a sharp band at 3580 cm −1 and absorption several times larger than unfractured samples. Microscopic examination of fractured samples showed that they contained water inclusions and healed fractures. Previous hydroxyl solubility measurements made on fractured samples may be too large due to hydroxyl contamination along fractures. At 900°C, experiments equilibrated in times consistent with a diffusivity for hydrogen impurity in quartz of 10 −7 cm²/s.