Effect of amount of material used on sedimentation slides in the control of illite "crystallinity" measurements
Lezzerini, Marco; Sartori, Franco; Tamponi, Marco
European Journal of Mineralogy Volume 7 Number 4 (1995), p. 819 - 824
published: Aug 1, 1995
manuscript accepted: Apr 14, 1995
manuscript received: Nov 2, 1994
ArtNo. ESP147050704009, Price: 29.00 €
Abstract The amount of material used on sedimentation slides is one of the main experimental factors affecting illite crystallinity" index (IC) determinations. The influence of this factor is re-examined here on three sets of pelitic samples from the Palombini Shale Formation (Northern Apennines, Italy), which has been subjected to conditions extending from late-stage diagenesis to low-grade metamorphism and which shows a wide range of IC The collected data show that IC values are strongly dependent on the amount of material when "thin" slides are used (loading of material less than 0.5 mg/cm2). For sedimentation slides with a loading greater than 0.5 mg/cm2, the variation of IC with the weight of the clay layer is much less marked, but not negligible. In a plot of "crystallinity" index (Ktibler index) versus material loading on the slide, the representative points define straight lines with a moderate slope; samples with different "crystallinities" are arranged on subparallel lines. Therefore, a procedure is suggested to normalize the IC values to a selected reference amount of material.