I am reading a book on Money by an occult writer, Frater U.D. Money Magic - Mastering Prosperity in its True Element. (His more interesting book is on sex magic, btw.) The author correlates wealth in the form of real estate and land clearly to the magical element of earth, but considers financial transactions a means of communication, becoming meaningful and valuable only in the act of exchange, and therefore correlates it with the magical element of air. Money isn't really bulky enough to qualify as earth, for example when a $ 20 bill flies out of one's back pocket. Even the credit card that dropped out of my back pocket into a toilet bowl last night - more on the airy side.
From this perspective, the interesting, important and valuable thing about money is its power of connection, exchange. In fact, money is the very act of exchange, of trans-action. "Humans are the only living creatures known to have developed this specific form of social interaction." (p.28 of the First English Edition) Regarding exchange via money as a social transaction, this currency becomes vibrant, alive, and filled with the qualities of the exchange it carries.