This was designed as part of a philosophical belief-system refit I've been doing lately. I've never liked the five element model... it's lopsided. Three is stable, five is an innately unstable number. Not to mention the fact 'spirit' isn't, in my book anyway, an element. Elements are things. You can feel the air, you can touch the earth. You can even put your hand in fire, though it's stupid. ^.^
Spirit, you cannot touch. It's not a /thing/, it's an ephemera. Spirit exists in all things, so it is not singular. Elements, by definition, are composed of no other thing but that which they are. So it's not an element.
As a result, I kept the four alchemical elements, and then added in two from Eastern belief to fill out the cycle. Wood is the only element that truly lives. It is all things natural, the living breathing world. Its counterpart, of course, is Metal... the artifice of man, the cogs and gears of the modern world, and these days, something you cannot ignore. While a lot of pagans would like to return to a more rural state of existence, I'm not one of them... and I am glad to include the elegant machinery of Metal in my belief system.
I have spirit-eidolons for most of these, but I haven't found them all just yet so until then you'll just have to make do with the sigils. ^.^