Rock Dust on the cheap!

Have you been snookered into buying Azomite? Well I was! I think it is a very nice profile but it is around $30 for a 50# bag. I made some calls to various quarries, and most of them will give you their assay of mineral content. This is not a complete profile, but pretty decent. And free!

Since the dust is the least marketable thing they make (it is basically waste from the crusher) generally you can get it under $20 a ton! Some smaller operations will give it to you!

I started this after reading Bryant Redhawk's post on soil, because for many of us with depleted soils this is a major reason for poor growth and plant sickness. This year I am going to use granite dust, the next time around I may need basalt, which has a higher metallic component. I am going to run a complete mineral test every year, but the dust is so cheap you might just want to empirically treat.

Azomite  mineral assay shows it is actually pretty deficient in iron, which has been a problem in some of my beds, while some of the local dusts (both granites by the way) have quite a bit more. One of the companies MSDS shows the basalt around here has much more magnesium and iron. So often there are different available dusts pretty close by. Folks in the red clay areas might want a nice low iron content dust. I have two assays from quarries not more than 10 miles apart in the images and the profiles are totally different!

One other word on these, many times the shipping is more than the dust, so if you have a couple friends who could use 5 tons (it's about a yard of material per ton) you drop your price dramatically by splitting a delivery. There is also a website called rockdustlocal that has done detailed assays on dusts and may be able to hook you up with a good profile, I am sure they charge something for their service, but it might be worth it if you don't know where to start on the quest for super soil.

Happy soil building!

Very cool!! Thanks for the info!

Iron is always going to be higher in Igneous rock dust than other types of rock dust.

One of the best profiles I've come across was from a "normal" lava flow that had been put through a hammer mill crusher, the mineral profile was really good, almost as complete as sea water for the majority of higher than trace amount minerals, Fe, Mg, Mn, Co, Cu and many others.

These are the main minerals you can find in magma as it comes out of the volcano. It is also why so many plants do so well in Hawaii, all that soil is based in weathered down lava and so super mineral rich.