Nontronite Minerals
Nontronite is a clay mineral that belongs to the smectite group, which also includes minerals like montmorillonite and saponite. It is named after the town of Nontron in France, where it was first discovered. Nontronite is commonly found in low-grade metamorphic rocks, hydrothermal deposits, and weathered volcanic ash deposits. This mineral is known for its green color, which can vary from pale green to dark green, depending on its iron content.