John Arthur Phillips FRS, FCS, FGS (1822 – 1887) was a St. Austell – born geologist, metallurgist, and mining engineer.
After initial training as a surveyor he changed to the study of metallurgy and electricity, concentrating in his early years with Robert Were Fox the Younger (July 25th) on the electrochemical deposition of copper from copper ores.  Phillips studied at the École des Mines de Paris for two years, graduating in 1846. 

Following two years as a metallurgist in a French colliery, he returned sufficiently renowned to be appointed to be a chemical advisor government commission advising on the question of coal for the Royal Navy and manager of several chemical works.  Subsequently, he became a freelance mining engineer and consulting metallurgist, progressing to appointments as Professor of Metallurgy at the College for Civil Engineers, Putney and as a lecturer at the Royal Naval College, Greenwich. Phillips became internationally famous and was invited to California, continental Europe and North Africa.  He made his fortune from his involvement in the Widnes Metal Company and retired from business in 1877 in order to concentrate on his research. 

He became renowned for his use of the polarising microscope in mineralogy and pioneered the study of the microscopic structure of minerals and rocks and the preparation of slide sections.  He published a number of authoritative works including ‘The Mining and Metallurgy of Gold and Silver’, ‘A Manual of Metallurgy’ and ‘A Guide to Ore Deposits’.