A method to determine crystallization temperatures of hydrated crystals by intracrystalline oxygen isotope effects

Oxygen and Hydrogen Isotope Effects in Low-Temperature Mineral-Water Interactions

“…Heinzinger and Götz (1975) showed that the fractiona tion of oxygen isotopes among different sites of CUSO4 · 5 H2O varied suf ficiently with temperature to be used to estimate the temperature of crystalhzation. These fractionations can be measured in cases where it is possible to dehydrate the crystal in a series of discrete steps, each increment of water lost corresponding to water in a different position.…”

The Dependence of the Oxygen Isotope Fractionation in the Hydration Water of CuSO4 · 5 H2O on the Crystallization Temperature

“…This method has a decisive disadvantage because in general the saturated solution from which the minerals were crystallized is no longer available and so the standard to which the isotope ratio of the hydrated crystal could be related is lacking. The advantage of the method described for CuS04'5 HOO as an example is that all required information for the determination of the crystallization temperature is deducible from the hydrated crystal alone by means of intracrystalline isotope effects 16 . No information about the mother liquor is necessary.…”