Swelling minerals in a basalt and its weathering products from Morvern, Scotland: II. Swelling chlorite

Abstract

A swelling chlorite from unweathered basalt has been characterized by XRD, IR, DTA and chemical analysis. Its 001 spacing of 14.9 Å increases to 18.0 Å on treatment with glycerol and decreases to 13.9 Å (with a broad diffraction effect at 14-10Å) after heating to 550°C. The mineral has an 060 spacing of 1.537Å consistent with a trioctahedral composition, but its OH stretching band at 3638 cm⁻¹ does not show the expected pleochroism, suggesting an anomalous hydroxide sheet which chemical analysis shows is incomplete. Although the mineral has a CEC of ∼50 mEq/100 g, smectite is not present, but all the techniques show that the mineral has some saponitic character, indicating that it probably has a structure intermediate between swelling chlorite and saponite.