Hornblende is a complex mineral belonging to the amphibole group, primarily composed of iron, magnesium, and aluminum silicates. It typically appears in dark green to black colors and has a prismatic crystal structure. Hornblende is commonly found in igneous and metamorphic rocks, such as granite and gneiss, and plays a significant role in the formation of these rocks. This mineral is important in geology as it helps scientists understand the conditions under which rocks form. Hornblende can also indicate the presence of certain elements, making it useful in mineral exploration. Its durability and resistance to weathering contribute to its presence in various geological environments.