The boom years 1844-1850
Post-boom years 1851-1861
Civil War years 1861-1865
Postwar years 1865-1880
Expansion Period 1880-1900
Twentieth Century 1900-1967

Very little information is available from this time period, especially when so many companies existed on paper only.
After the War Department began accepting applications for mining permits in 1843, the rush was on.  However, only a handful of companies actually started to do any real mining.
Here some early companies and a brief description of their success, or failure.