Showing papers on "Portlandite published in 1984"

Calcium and magnesium hydroxide precipitation from alkaline groundwaters in Oman, and their significance to the process of serpentinization

Abstract: The occurrence and genesis of Ca(OH)2 and Mg(OH)2 deposits associated with hyperalkaline ground- water from partly serpentinized ultramafic rocks in Northern Oman is reported. Two types of Ca(OH)2 deposit are differentiated; crystalline portlandite formed by the evaporation of Ca 2 +-2OH- spring waters, and a form of amorphous gel, not previously known in nature. The latter is a product of present-day low-temperature serpentinization. Mg(OH)2 (brucite) in both holo- crystalline and gel forms is produced by mixing of Mg 2+ 2HCO~ surface waters with a Ca2+-2OH - groundwater in both surface and groundwater environ- ments. These results indicate that significant differences exist between the processes of medium- and low- temperature brucite generation.