The direct derivation of cordierite from a clay-chlorite precursor

Abstract

A dioctahedral chlorite (arguably sudoite) in a drill core from the syngenetic stratiform Geco orebody has a composition reminiscent of cordierite, with which it is closely associated although mostly in separate grains. The sudoite is interpreted as a precursor to cordierite. Those grains or parts of grains with significant amounts of interlayer cations survived metamorphism and are relics from the hydrothermal sedimentation-diagenesis stage of ore formation. This paper is a splendid illustration of the proposition that metamorphic minerals are developed from particular precursor materials and that a highly localized development of very complex metamorphic mineral (high-Al) assemblages reflects the hydrothermal conditions of exhalative deposition and alteration, and are thus guides to such ores.-G.J.N. Show more