Dr. Leon James Halloran, age 77, of Elgin, IL, passed away on December 30, 2024. Son of the late Leo and Mary (née Defferding) Halloran, and husband to Douglas Taron, Leon was born September 14, 1947 in Roseburg, OR and raised in Myrtle Creek, OR.  He graduated in 1965 from Myrtle Creek High School.

Leon graduated in 1969 from Oregon State University where he majored in chemistry.  He attended graduate school at Washington State University where he received his Ph.D. from the department of chemistry in 1974.  His dissertation research involved the use of x-ray crystallography to determine the three-dimensional structures of coordination complexes of cobalt.  Leon held a postdoctoral position for two years at Michigan State University before moving to the Chicago area where he worked as an analytical chemist for Universal Oil Products (later acquired by Honeywell) until his retirement in 2016. 

Leon and Doug shared a passion for nature and the environment. Beginning in the early 1980's, they were stewards at the Bluff Spring Fen nature preserve in Elgin.  There they participated in protecting the site as an Illinois Nature Preserve, monitored a variety of imperiled species, and provided hands-on management activities such as brush clearing.

Leon loved hiking, backpacking, and travel. His backpacking exploits, often with Doug and dear friends Ron and Sharol Crandall, spanned many decades and included many trips to the mountains of the West. He was especially fond of the Sierra Nevada and the Grand Tetons.  He and Doug traveled extensively, and visited South Africa, India, and numerous countries in Europe and Latin America.

Leon is survived by his sister Kathi Halloran and her husband Bill Siling, his niece Taylor Halloran Siling, and numerous cousins.  He was preceded in death by his parents and his brother Laren Halloran.

A memorial gathering for Leon will be announced at a later date.  Interment will be private.

Final arrangements entrusted to Symonds-Madison Funeral Home. For more information, call 847-741-1128.