Other gold deposits were found in Montana resulting in considerable production — and the geology of the state indicates that there are many other deposits that remain to be discovered.
Several have already been identified. Finding gold requires good geological detective work. The US Geological Survey ranked Montana as number 7 in gold production in the US and reported that the state included 31 gold mining districts.
Total gold production from the 19th century to was Based on geology, it is predictable that several large undeveloped and undiscovered gold deposits will be found, identified and developed in the future. The principal placer districts are in the southwestern part of the State.
Other important localities are on the Missouri River in the Helena mining district. The famous Last Chance Gulch is the site of the city of Helena. There are many districts farther south on the headwaters and tributaries of the Missouri River, especially in Madison County which ranks third in total gold production in the State. Gold was produced at many places on the headwaters of the Clark Fork of the Columbia River, particularly in the vicinity of Butte.
Placer production from the Butte district, however, has been over-shadowed by the total output of byproduct gold recovered from the mining of lode deposits of copper, lead, and zinc.
Following discovery of significant gold in the streams within the Bannack district inthe precious metal was mined along a mile stretch of Grasshopper Creek and several tributaries at the southern end of the Pioneer Range. Mining included placer, hydraulic and some lode activity during the period of toand dredging occurred on Grasshopper Creek from to More thanounces of gold were recovered from placers while the lodes only produced 35, ounces of gold. The geology of Bannack was described by Winchell as consisting primarily of Paleozoic Madison Limestone.
Immediately above the Madison are remnants of the Quadrant Quartzite. These sedimentary rocks were intruded by granodiorite that is nearly circular in plan on the south side of Grasshopper Creek.
A minor granodiorite intrusion is also found on the north side of the creek to west of Bannack. The eastern portion of the district is overlain by Tertiary volcanics. Lode deposits are interpreted contact replacement mineralization with some fissure veins. The ores are dominantly gold with some silver, lead and copper and generally found along the contact between the limestone and granodiorite, or in stringers or small fissures. Large amounts of garnet, with some epidote, are also along the contact.
The underground workings were ultimately integrated through an extensive network of more than 18, feet of drifts, winzes and raises which connected to a series of ore shoots on different levels of the Dunn, Priscilla, Golden Leaf, and Thompson lodes.