| Lead mining boom in Platteville attracts large mining operations.
| The majority of African Americans in the region become free. Some continue to mine and form communities such as Pleasant Ridge.
| Zinc mining, originally for smithsonite, takes over as the predominant focus of Platteville mining companies.
| The zinc ore known as sphalerite becomes the main mineral mined in Platteville.
| Simon Ingersoll invents the steam-powered percussion drill, greatly improving productivity in Platteville’s mines. He forms the Ingersoll Drill Co. in New York, NY.
| Ingersoll’s former business partner, Henry Clark Sergeant, forms the Sergeant Drill Co. in Bridgeport, CT. Sergeant begins to improve on Ingersoll’s original work by replacing steam-power with compressed air power (pneumatic).
| Ingersoll-Sergeant Drill Co. is formed by consolidating the two inventors’ respective companies. It is during this period before 1905 that the pneumatic drill currently at Rountree Hall is manufactured.
|1890 to 1920
| Eastern European immigrants arrive in Platteville to work in the mines.
| Ingersoll-Sergeant consolidates with Rand Companies to form Ingersoll- Rand, which is still in existence today.
|1905 to 1906
| The Platteville zinc boom is in full swing, and more than 31 mining companies incorporate in Platteville alone and sell stocks.
| The Wisconsin Mining Trade School in Platteville is established at Rountree Hall to train mining technicians to work in the local mines.
| The school becomes the Wisconsin Mining School. It focused on training mining engineers and technicians for work in mining operations around the world.
| The school reorganized itself under the name the Wisconsin Institute of Technology to show its engineering and mining strengths.
| The Ingersoll-Sergeant drill is placed in front of Rountree Hall, then part of the Wisconsin Institute of Technology.
| The Wisconsin Institute of Technology merges with the Platteville State Teachers College to eventually be known as the University of Wisconsin – Platteville.
| The final mining operation in Platteville closes.