Complex sentence: Henry Frank also co-owned an important mining company "Canadian-American Coal and Coke Company" in the town of Frank, Alberta, Canada, which was damaged in the famous Frank Slide of 1903.
Split into simpler sentences: Henry Frank also co-owned an important mining company "Canadian-American Coal and Coke Company" in the town of Frank, Alberta, Canada. The mine owned by the company was damaged in the famous Frank Slide of 1903.