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How are the axes arranged in the isometric crystal system?

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A rough, translucent yellow crystal of elemental sulfur displayed against a solid black background. — crystal A crystal form of elemental sulfur. Sulfur has an atomic weight of about 32.06 atomic mass units (amu), which means that its molar mass is 32.06 grams.

In the isometric system (also known as the cubic system), the crystal structure is defined by three mutually perpendicular axes of equal length, designated as $a_{1}$ , $a_{2}$ , and $a_{3}$ .12

These axes serve as the reference lines for describing the internal atomic arrangement and the geometry of the unit cell. Because these three axes are equal in length and intersect at right angles, the resulting unit cell is a perfect cube. Additionally, the isometric system is characterized by four axes of threefold symmetry, which correspond to the diagonals of the cube.2