[zakelwe]

Crystalline rocks will always have some specular part due to them, er containing crystals. Such as granite. Some metamorphic rocks would not show as much spectacular specular ( sorry, I had to to get that in , hoping to get rocks for brains in there as well later) such as limestone or slate unless wet

Albedo is a property that nobody has mentioned yet, ie how much light is absorbed or reflected. The moon has a low albedo so is quite dark though you would not know it of course looking at the sky.

I did all that without using Google, are you all impressed ? it's probably all the wrong way around !

Regards

Andy