Why use x-rays to study crystals?

[chukie]

In order to study the structure of crystals, scientists normally use X-rays. Why do they use X-rays and not visible light?

I'm thinking it has something to do with wavelengths, but I do not know why the difference of wavelength matters.

 

[gendou2]

Visible light has a large wavelength, too large and clumsy to be helpful on the atomic scale.
X-rays, on the other hand, have tiny crisp wavelengths, perfect for examining crystalline structures.

 

[chukie]

thanks!