Finely Ground Quartz : Evidence against a ‘Disturbed’ Layer

Abstract

BRISCOE et al. ¹ discovered that the rate of solution of a finely ground quartz powder decreases slowly from an initially high value to a much smaller steady value. Kitto and Patterson² concluded that the effect could not be accounted for on the basis of particle size alone and attributed it to edge effects and the presence of a ‘Beilby layer’, presumably of amorphous silica. Further evidence of an amorphous layer has been reported by various authors using X-ray diffraction^3,4, electron diffraction⁵, differential thermal analysis^6,7, rate of solution^8,9, and density^6,9 measurements. Some, not wishing to commit themselves as to its exact nature, have called it a ‘disturbed’ layer. Estimates by a variety of methods^3,5–9 put the thickness of the layer at between 300 Å. and 1,500 Å.