Fundamental particles: an informal history

An informal overview is given of the development of the fundamental particl e model, where, in a series of papers published from 1982-1957, researchers from the Macaulay Institute presented a radical model for the interpretati on of the crystal structure, chemistry, and genesis of interstratified clay s. The model reconciled electron microscopy and X-ray diffraction (XRD) dat a from a variety of sedimentary clay specimens, and proposed that these min erals were composed of nano-crystalline 'fundamental particles' whose adsor ptive interfaces were responsible for the expanding smectite layers observe d by XRD. The term 'interparticle diffraction' was used to describe this ph enomenon. Experiments were reported which proved the model, by producing ra ndomly interstratified illite-smectites from combinations of ordered illite -smectite and smectite clay dispersions. The model was extended to propose that fundamental particles were the primary units of crystallization, and t hat changes in the pal-ride population were responsible for the commonly ob served evolution in XRD character of these minerals with increasing depth o f burial and temperature.