"Hittel on Gold Mines and Mining" is about the gold mining industry in the Pacific states, primarily California and Nevada, during the mid-19th century. The book covers the history of gold discovery, the geology of gold-bearing regions, and various mining techniques used at the time. It also discusses the economic and social impact of the gold rush, providing insights into the challenges and opportunities faced by miners. Hittel's work is a valuable resource for understanding the development of mining in the American West and the broader implications of the gold rush on American society.