Biotite is a common mineral found in many types of rocks, especially in granite and gneiss. It belongs to the mica group and is known for its dark color, which can range from brown to black. Biotite has a layered structure, allowing it to be easily split into thin sheets. This property makes it useful in various applications, including as a heat-resistant material. In addition to its geological significance, biotite plays a role in soil formation and nutrient cycling. It contains essential elements like potassium, which can be released into the soil as it weathers. This process helps support plant growth and contributes to the overall health of ecosystems.