Chris Riddle

Determination of chemical water in rock analysis by Karl Fischer titration

Abstract The potentiometric Karl Fischer titration method has been adapted for the determination of combined water in chemical rock analysis. This procedure appears to be superior in accuracy, precision and rapidity over the well-established Penfield method. Determination of water in copper sulphate pentahydrate is at the theoretical limit within experimental error. We also report replicate determinations by both methods on five samples, including the international standard BCR-1.

Ferric/ferrous-iron ratios in bulk rock samples by Mössbauer spectroscopy — The determination of standard rock samples G-2, GA, W-1 and mica-Fe

Abstract Room-temperature 57Fe Mossbauer spectra have been recorded for the USGS rock-standards G-2 and W-1; the CRPG standards GA and mica-Fe; and an “in-house” standard, NS. A comparison of the results of ferric/ferrous-Fe ratios by chemical and Mossbauer analysis is presented. The errors involved in each method are assessed. In the low-Fe rocks, chemical analysis appears to considerably over-estimate ferric content although the spread of individual laboratory values tend to a low limit close to the Mossbauer values.

Determination of carbon dioxide in rock analysis by non-aqueous titration

Abstract The determination of CO2 by non-aqueous titration against sodium methoxide, using thymolphthalein indicator, has been applied to rock analysis. Replicate determinations are reported for CO2 in the international standards SY-2 and BCR-1, and in an “in house” standard, NS. Comparative data are also presented for the conventional volumetric and gravimetric methods. When the procedure is combined with the titrimetric method of chemical-water determination, using a split-flow technique, simultaneous determination of H2 O and CO2 may be effected.