Derain is a crater on Mercury. It has uncommonly dark material within and surrounding the crater. The material is darker than the neighboring terrain such that this crater is easily identified even in a distant global image of Mercury. The dark halo may be material with a mineralogical composition different from the majority of Mercury’s visible surface. (wikipedia entry)
A crater is a circular depression likely created by an impact event. On Mercury they are named after deceased artists, musicians, painters, and authors who have made outstanding or fundamental contributions to their field and have been recognized as art historically significant figures for more than 50 years.
Image Source. Marker locations are approximate and may not always appear to align with image on map.