Crystal Structures of Minerals

What crystal structure has three axes, all perpendicular to one another and all equal in length?

What crystal structure has three axes of unequal lengths, two of which are oblique not perpendicular to one another, but both of which are perpendicular to the third.

What crystal structure has four axes, three of these axes are in a single plane, symmetrically spaced, and of equal length, and the fourth axis is perpendicular to the other three.

What crystal structure has three axes, all perpendicular to one another, and two are of equal length?

What crystal structure has three mutually perpendicular axes, all of different lengths?

What crystal structure has three axes, all unequal in length and oblique to one another?