Okay then, fufufu. In order to understand what the components of the symbol reflects, we'll have to skim over a few rudimentary concepts of alchemy.
The Emerald Tablet teaches us that 'That which is above is like that which is below'. The same scale that manifested the planets manifested the metals. The planets themselves are said to have influenced the birth of metals in the womb of the earth--not physically, but in essence, as according to two poles of existence: passive (silver) and active (gold). The planets and metals are reflections of an ontological scale which measures and connects Heaven and earth in grades between silver and gold.
Another concept is the rotation of the four elements as described by Aristotle. Again, this isn't taken in a literal sense, but in a cosmic sense for classifying the characteristics of matter. The four elements have properties (hot, cold, wet, dry) that are found in one another to describe mutability in creation. The four elements are:
Fire: Heat, dry
Air: Heat and moisture
Water: Cold and moisture
Earth: Cold and dryness
The four elements also correspond to the four cardinal directions of space which form the cross of matter.
The symbols for the metals and the planets are comprised of a circle (gold and the sun),a semi-circle (moon and silver), and the cross (four elements of matter).
The symbol for Hermes / Mercury / Quicksilver is composed of all three components: the crescent, the circle, and the cross. The crescent represents the moon, passivity, and materia prima(the base matter), which is also the soul as passive matter. What links the cross of matter with the crescent is the sun, which represents spirit and gold. The impression left is that this sign expresses materia prima as the container of all forms. There's a lot that can be said about the sign, but it's basically the key to alchemy.
So INFJs are taking over the forum? That's pretty cool. \(*w*)/
P.S. I win, but this is no surprise: I ALWAYS win.
Interestingly enough, I have a tattoo of the alchemist symbols for the elements.