William F. Bradley

1908 to 1973
Clay Mineralogy

William F. BradleyWilliam F. Bradley was born in Quincy in 1908. He entered the University of Illinois in 1925 and earned a B.A. in geology in 1930. He completed a Ph.D. in 1935 after graduate studies of the X-ray diffraction of clay colloids in Professor Clark's program at the University of Illinois Chemistry Department. He joined the Illinois State Geological Survey as Assistant Chemist in 1934, was promoted to Associate Chemist in 1939, and served as Chemist and Head of the X-ray Division from 1946 to 1961.

Bradley served as a visiting professor in a new material science program at the University of Texas, Austin, during spring 1959, and he left the Survey in 1961 to spend 12 years as Professor in the Chemical Engineering Department at University of Texas. While there, Bradley returned to the Survey most summers, where he conducted research with H. D. Glass and others, reviewed papers and research results for several scientists and students, and advised visitors on new directions they might pursue. Bradley also consulted for Shell Oil for many years, and he was an integral part of the internationally recognized clay minerals group at Shell. He served at Texas until his untimely death in a 1973 auto crash. Bradley is interred at the Mt. Hope Mausoleum just south of the Survey.

It is impossible to summarize Bradley's career in this short biography, but his 70 papers included some true benchmarks. His skills in crystallography and X-ray diffraction perfectly complemented Ralph Grim's abilities, and Bradley is central to many early publications and the Survey's justly earned reputation as the birthplace of clay mineralogy. Bradley truly understood mineral crystallography, and his early publication on the structure of attapulgite (palygorskite) and rectorite are classics. With Grim and R. H. Bray, he published the earliest paper on illite, and that paper{\u8217\'92}s broadening of the definition of a mineral paved the way for later understanding of detrital and diagenetic illite, mixed-layered illite/smectite, and estimates of the age and chemical changes in sediments during diagenesis. These insights made major contributions to oil and mineral exploration, and illite is now widely used to reconstruct the history of basins and mountain ranges.

Bradley was a leader in establishing X-ray diffraction quantitative methods, and he used these methods to analyze hundreds of samples for Survey scientists and for some early studies of deep sea sediments. His list of publications is a worthy review for anyone interested in the growth of this field. Bradley also was of a humble nature, and he had an understated wit. He was so talented that, despite his unassuming ways, he was elected to the highest offices of his societies. He received early recognition as a distinguished member of the Clay Minerals Society and the Roebling Medal of the Mineralogical Society of America.