For more information, see the interesting article “The Origin and Development of the Source Clays Program” contributed by William F. Moll
By the early 1970’s the need for sources of homogeneous clay samples had become apparent to researchers. Natural deposits are so variable that data generated by different investigators working at the same outcrop often cannot be compared with confidence. Thus the Clay Minerals Society set up the Source Clays Project.
The Society’s Source Clays Repository offers two series of materials, the Source Clays and the Special Clays.
Starting in 2015, The Society’s Source Clay Repository also sells the leftover reference mineral mixtures from the Reynolds Cup contests . The materials, Reynolds Cup Reference Mixtures , are useful for checking analytical procedures.