What does it look like?

The crystal structure of Bonnattite. The blue atoms are copper, the red oxygen and the yellow are sulfur. Image generated by the VESTA (Visualisation for Electronic and STructual Analysis) software http://jp-minerals.org/vesta/en/

What is it

Discovered in the Toscana region of Italy Bonattite is very similar in composition to copper sulfate pentahydrate, except it has only three water molecules in its structure making it a copper sulfate trihydrate.  There’s not much information out there on this illusive mineral, but is thought to form in hot spring areas like Steamboat Springs in Colorado.

Where did the structure come from?

The structure of Bonattite was determined by Zahrobsky and Baur from an synthetic sample in 1968.  You can find this structure in the American mineralogical database.