1991 Volume 32 Issue 5 Pages 221-231
Laumontite and montmorillonite, known as reactive minerals in concrete, are often observed in some quarry sites of the “Green Tuff Region”. Laumontite and interstratified chlorite/smectite in aggregates from Miocene volcanics were analysed with an X-ray powder diffraction method quanitatively.
An internal standard method was used to avoid the dependence on the mass absorption coefficient and the analytical conditions were selected experimentally. Errors in measurements without monochrometer are as follows,
laumontite (1-2%): 2σ=±0.17% (detective limit: 0.3%)
disordered chlorite/smectite interstratified mineral (10-20%): relative error ±25%
Influence of the X-ray peak of coexisting stilbite and mordenite on that of laumontite are correctable. The probabilities of existence of component layers in the interstratified minerals were obtained from the X-ray profiles from samples immersed in ethylene glycol. The ratio of interstratified chlorite and smectite layers can also be estimated from the intensity ratio of (001) / (002) peaks without any chemical treatment.
