C) Phosphate
Phosphate was discovered near Dunnellon, Florida in 1889 by Albertus Vogt. Soon after, the Dunnellon Phosphate Company was formed, and mining of high-grade phosphate began. Thousands of prospectors moved into Florida and by 1894, over 215 companies mined phosphate there, causing an economic boom. Furthermore, land prices per acre skyrocketed, climbing nearly sixty times its price before the boom.