Here's an interesting topic, the colour of the Moon. "What colour?" I might hear you ask. The Moon appears completely grey to us (not counting the times when it appears yellow / orange / red due to atmospheric effects or lunar eclipses).
In fact, there are subtle hues in the lunar surface, our eyes are just not that good at picking them. These subtle hues can be seen on some photographs of the Moon, the colours can be digitally enhanced, and you can even see subtle colouration when using binoculars or a telescope.
Two major colours that can be picked up are blue and rusty-brown. The blue is found mostly in the Sea of Tranquility and is caused by titanium-rich minerals. The rusty-brown is caused by iron-rich minerals.
Below are two photos of the Moon, one without any colour enhancement, and the other with enhanced colours:
Colour of the Moon is discussed in great detail in this article: http://www.colormoon.pt.to/
I also run a Facebook group dedicated to this topic: Colour of the Moon
Next time you look at the Moon through binoculars or a telescope, see if you can catch a hint of slate-blue colour in the Sea of Tranquility, it's the easiest to spot.