This book serves as a comprehensive record of mineral production within California for the year 1942, detailing the state's geological resources and the entities involved in their extraction. It compiles data on various minerals, their quantities, and values, alongside a directory of the companies and individuals responsible for their production. The work is grounded in official records and industry reports from the period, aiming to provide a factual snapshot of California's mining sector at a critical point in history.

This publication is a historical reference document, likely valued by researchers, geologists, and historians interested in California's industrial past. Its utility lies in its detailed, factual compilation of data from a specific year. The authority perspective would emphasize its role as a primary source for understanding the state's mineral economy during World War II.