👉 Polyurias is a term used in geology to describe rocks that are composed of several different types of minerals, such as quartz and feldspar. These minerals can be found together in a rock, making it appear like a single material. This type of rock is often called a biotite or a biotanite. Polyurias can also refer to the presence of multiple layers of minerals in a rock, which can make it appear more complex and varied than a simple mineral bed