My observation reminded me of the historic observations made by Antoniadi and Schiaparelli over the end of the nineteenth century and early twentieth century. These classic astronomers made their observations of Mercury in the daytime as observing this planet is difficult in a darkened sky as it is never more than 28 degrees from the Sun. Schiaparelli and Antoniadi erroneously believed that the rotation period of Mercury was 88 days (instead of 58.6 days) and therefore locked in with it's revolution period. It was not until 1965 when the Arecibo radio telescope discovered the true rotation period.
A digital image produced in Photoshop CS3.
BE CAREFUL TO NEVER OBSERVE MERCURY IN THE DAYTIME UNLESS YOUR INSTRUMENT HAS A SOLAR FILTER PLACED UPON IT UNTIL THE PLANET IS IN THE FIELD OF VIEW!