CSD is a repository for small-molecule organic and metal-organic 3D crystal structures, containing over 875,000 entries from x-ray and neutron diffraction analyses.
Includes every structure published in the major mineralogy journals. Search by mineral, author, element names, cell parameters, etc. Here's a description from the journal.
Crystallographic database and programs aimed at analyzing, calculating and visualizing problems of structural and mathematical crystallography, solid state physics and structural chemistry.
Open-access collection of crystal structures of organic, inorganic, metal-organic compounds and minerals, excluding biopolymers.