Gustav Jermy was born on 30 August 1833 in Késmárk, Hungary, the son of Carl Jermy and Maria Weisz, he was a high school teacher during the 1860's. He emigrated to America in the 1870's and settled in Texas, where he worked as a geologist for the Geological Survey. He married Rosa Gaál, also from Hungary, and they had two sons and a daughter.
He was the founder of the first museum in San Antonio.
Ref: Jermy, Gustav. 1888. Report of geologists for southern Texas. First Report of Progress. Geological Survey of Texas. p61-64.