Montana Water Well Contractors Practice Test

The primary composition of bentonite is swelling sodium montmorillonite, which is a type of clay mineral that belongs to the smectite group. This specific characteristic of montmorillonite contributes to the unique properties of bentonite, such as its ability to swell significantly when exposed to water. This swelling property makes bentonite particularly useful in various applications, including drilling fluids in well construction, as it helps maintain the stability of the borehole and seal off water-bearing formations.

While bentonite may contain other materials or impurities, its defining characteristic is the presence of the sodium montmorillonite mineral. Understanding this composition helps in recognizing the performance and application of bentonite in water well drilling, as well as its role in controlling fluid loss and providing lubrication during the drilling process.