This collection highlights the career and research of H. Mason Coggin, a professional engineer and land surveyor and expert in gold placer mining. Although the collection's main focus is on gold placer mining, all aspects and types of mining are represented. This collection may be the most comprehensive contemporary mining collection available. Please note that many files have duplicative titles in different series. However, the information contained within varies significantly. It is suggested that a researcher working on a particular mine, company, or topic request relevant files in each series. The collection is arranged into five series: Series I: Business; Series II: Mine Files; Series III: Mining Companies; Series IV: Reports; and Series V: Research Files. Series I: Business is divided into seven subseries; bids and contracts, calendars, correspondence, design files, investment opportunities, projects, and registrations. Bids and contracts document the process of obtaining a specific project. Of interest are Coggin's calendars and correspondence that document his work at Coe and Van Loo Consulting Engineers as well as his own private consulting firm. Design files contain information on the latest design techniques for equipment and mining processes. Files on investment opportunities often include an insider's look into special mines not known about by the public. Projects contain reports, data, and background information on individual projects by a certain company or on a specific mine. Registration files document the paperwork and applications necessary to practice in each given state. Series II: Mine Files is divided into three subseries; Arizona mines, out of state mines (other than Arizona), and the IMI Property Database printout. Both Arizona mine files and out of state mine files include reports about each mine, background and historical information, mining districts, maps, plots, assays, and legal documents. All files, if known, contain the county of the mine since some duplicative naming exists. Of note, many files include copies of maps for properties that date as far back as the late 1800's. Included in the Arizona mines subseries are general county files. Also included in this series is the IMI Property Database printout which lists active mines in their respective states. Series III: Mining Companies includes background information on mining companies worldwide. Files consist of reports, history and background of the company, projects completed, and financial statements. Of interest are files relating to large mining operations such as Phelps Dodge, Superior Companies, and Mines West, Inc. Series IV: Reports includes both general reports and property reports. General reports range in topic from cole leasing to the status of mining in Angola. Property reports highlight specific mining properties. Additional information for specific properties can also be found in Series II: Mine Files under the name of each mine. Series V: Research Files include various topics ranging from general information about gold placer mining to specific mining techniques and processes, important figures in the mining community and publications.