The seven unique crystal types are defined by what parts of themselves (parts that intersect at various angles)?
eyes
shards
angles
faces
Crystals are classified into general categories based on their shapes. A crystal is defined by its faces, which intersect with one another at specific angles, which are characteristic of the given substance. The seven crystal systems are shown below, along with an example of each. The edge lengths of a crystal are represented by the letters , , and . The angles at which the faces intersect are represented by the Greek letters , , and . Each of the seven crystal systems differs in terms of the angles between the faces and in the number of edges of equal length on each face.