J -- Hmmm... That's a tough one. Since I have no Jadeite, Jeremejevite, Jarosite, Johannite or Julgoldite, and I have no decent pics of my Jamesonite, I'll have to use a proper name to fill this spot. J. Volney Lewis, Professor of Geology and Mineralogy at Rutgers College, who wrote one of the best books available at the time on Determinative Mineralogy.
http://www.etsy.com/listing/118159640/antique-book-determinative-mineralogy?ga_search_query=j