Laser Crystal Gifts

Why does the Orthorhombic crystal system have 3 different crystal types?

The Orthorhombic crystals have 3 axes at unequal lengths and faces at 90 deg angles. Why does this result in 3 different crystal types [dipyamid,prism, scalenohedron]? I think there should only be a single Orthorhombic crystal type as there is only the one, same set of axes? Obviously this is incorrect and I cannot see how the 3 axes at unequal lengths set produce three different crystals- all Orthorhombic. Any help is greatly appreciated. Thank you

Public Comments

1. The article below answers your question. As I understand it the three axes determine the regular, repetative internal structure, it is the combinations of this internal structure which give rise to three different crystal types. http://dave.ucsc.edu/myrtreia/crystal.html#ORTHO