Your kitchen cabinets contain a huge supply of subjects for a macro lens. Even though the Canon MP-E is capable of up to 5x magnification, any good 1:1 or 1x-capable macro lens lens can make your salt look like this.
Lighting for this shot is from a non-modified Canon 580EX II positioned just outside of the frame and remotely fired.
The salt was not so pure white - DPP's clone stamp tool was used to remove the brown spots.