Mineral Of The Day #134: Nontronite
Mohs Hardness Scale: 1.5-2
Category: phyllosilicate mineral, smectite group
- Nontronite is the iron-rich member of the smectite group of clay minerals.
- It forms from the weathering of biotite and basalts, precipitation of iron and silicon-rich hydrothermal fluids, and in deep-sea hydrothermal vents.
- Nontronite is named after its type locality of Saint-Pardoux, Nontron (Dordogne, France).