"Scientific analysis of this combination of volcanic ash and marine minerals reports over 70 trace minerals...."

Sounds interesting for use in soil-less media.

http://en.wikipedia.org/wiki/Azomite

I have been using it. I add about a cup when I prepare a new batch of potting mix.  I'm not sure how much it helps but my trees are all happy, of course I add a good deal of other things as well.
I have read a little more on it in the last couple days since Daniel/ediblelandscapingsc commented(not his exact words here, just the jist) he doesn't use it because of some possibly harmful contents. So I searched "Azomite harmful" and "Azomite risks" and read for a while. The radiation aspect was what I was most interested in. Azomite does primarily come from the earths magma core so most if not every element on earth is present..and the earth's core is sort of like a huge reactor so naturally there is remnant radiation. But, we evolved with that radiation present all over the earth so I'm not sure it is a issue. The radiation from man's experiments and mistakes, that is a different can of worms. I will probably end up doing more reading on the subject, problem is there are no real studies just a good deal of theory and opinion on the matter.

I've been thinking of trying some mixes with Azomite and Green Sand to see if they seem to help.  Anyone also using Green Sand?  That one seems less obvious regarding what it's bringing to the party, but people swear by it.

I use Azomite in combination with HP Pro-Mix and 18-6-12 Osmocote.

This was my first year growing, but from what I understand, trace elements (i.e. Azomite) are almost as important as fertilizer.

Yeah, I used some this past spring.  It does help.

I need to find this locally here in North Jersey. I have many 20 gallon up-pots I need to do in the spring and I'm considering adding this to my "Rich's Super Mega Mix".

Besides azomite and green sand, there is also glacial rock dust. I got azomite and glacial rock dust online.

I haven't used azomite but I routinely use greensand with my vegetable garden, fruit orchard and figs. I believe it helps provide trace minerals as well as potassium.