Finding and utilizing local sources of rock dust

This is a discussion facilitated by Tom Vanacore.  Please feel free to ask questions and respond with your  experience and know-how.

Tags: Rock, dust, local, sources

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From Tom Vanacore:

I started Rock Dust Local LLC, www.Rockdustlocal.com , to get local and regional rock dust sources to growers interested in using their local resources to best advantage. Since we live in Vermont I have been concentrating my efforts in the North East US, New England, New York and down into NJ and PA, but this can be done anywhere that suitable materials are being produced. I hope the Rockdustlocal website can provide people with local choices and we arrange for the delivery of materials suitable for their purpose. I am also fielding inquiries from folks where we have not yet identified local resources and if they are willing to do some leg work we are directing them to local resources based on their own search or based on ours. There is process involved and communications can be numerous before we get anywhere, but the process can also be rewarding when we find good sources with enthusiastic operators. Or, it can go the other way, if communications break down or the folks give up. I have been at this for 25 years and you meet all types.

Not all rock dusts are alike and some are certainly better than others for remineralization.  The only way to know the material is to have a petrology or analysis in hand and to try the material out to prove its worth. You can know a lot about the type of material if you understand something about geology and are ready to apply this knowledge to plant nutrition, soil biology etc. John Hamaker was a firm believer in the worth of glacial rock dusts, which can be found in just about any sand and gravel aggregates operation. His idea was to spread out the glacial dusts just as the glaciers did during the last ice age. At Rock Dust Local we focus on the igneous rocks, the magmas, volcanics, or sediments associated with these as well as the glacials.  The igneous Basalts are particularly valuable in that they are derived from the ocean floors and come up from the mantle of the earth, so they have pretty much everything in them.  Basalts can be found on land where the big geologic uplifts meet the mountains, often along the ocean shores. The North East has big deposits and the Pacific Rim has big deposits.  Other types of useful rocks are the Granites, which are traditionally used by berry growers and potato growers because of the potassium (K) associated with some of these. 

We found that most aggregates producers do not know what they are crushing, except whether it is a 'hard rock' or limestone. Even that is useful information, though.  "Rock dust" is not an industry term in the US though. So if you ask for 'rock dust' the sales person may correct you by using terms such as 'stone dust' or 'fines'. Or they may just say we don't have any. That will give you an indication that you may be in deep water trying to get what you want. This is one of the reasons we started the Rock Dust Local venue. I've worked in the stone business for 30 years so I have an understanding about the process and the concerns of the operators, as well as the bedrock geology.  What I want to avoid is folks arriving at commercial stone crushing and screening operations in their station wagons with kids and five gallon pails hoping to find a little rock dust. That won't help industry relations much. These are construction materials operations by and large and are often concerned with large scale road building and concrete, heavy equipment operating and trucking, with little time on their hands. They often have stacks of materials which can be useful as agricultural soil amendments, if their material is suitable, but getting the right stuff can be the challenge if you do not know what to ask for, or have no way of moving it, or only want just a little bit. This is one of the things we do in the process of identifying local and regional resources. We get to know the operators and fill them in on what we are after, which materials will work. We do the complete analysis and review the findings.  We will also ask them to make up a specific blend of materials suitable for broadcast spreading if they do not have one commercially available in their normal product line. And we deliver direct from the source to the grower. This is the service we provide if the grower would just ask us to do it and be willing to pay a little over our cost to cover our efforts. But, we will help anyone with their own quest wherever they are.

So to recap: Local aggregates producers are the best resources for 'rock dust' for remineralization, but geochemical analysis and geologic identification are key to understanding the value. Not all rock dusts are alike, not all are useful or desirable.   Glacial sand and gravel operations are good local sources generally. The igneous rocks are good, particularly the basalts, granites, and deposits of volcanic origin. Some quartzite or sandstones are very rich, but it depends on location. Some sedimentary rock is very excellent, but analysis is important. Heavy metals, toxins, radioactive materials, contaminants, and other undesirable materials may be present in certain deposits. By and large commercial rock dusts associated with approved aggregates operations are free of toxins, but certain geologic types tend to concentrate the heavy elements, so these must be quantified. Understanding the manufacturing process and the concerns of the operators is essential, particularly their concern about getting their work done and the need for safety. (Do not wander into a crushing operation with your 5 gallon pails and kids in tow!) Work with Rock Dust Local (Rockdustlocal.com) or your regional operator, or both, to establish the suitability of your local materials for agriculture or forestry. We're here to help and there is plenty of material to go around and plenty of sources to locate and evaluate the world over. This is truly a local geo-engineering initiative which can help the process of revitalizing the earth's green mantle, the oceans, and recapture atmospheric carbon by sequestering in growing mediums and plants.  

Tom V

Rockdustlocal.com

Rockdustlocal.com

One of the main goals of the online community is that if you find a local source of rock dust and you get good results with it, that you let us know and we will be putting it in a database dedicated to making that information available. Great if people can find out about it here first.

Through experiences of all of you we can refine the search process, especially with  Tom's facilitation and expertise.

This should give us a great deal of momentum. Thank you all!

Joanna 

This is not a specific source of rock dust per Se but a good one nonetheless. I participate in a Native Sweat Lodge here in Hamilton. The sweat requires heating dozens of 5-10 lb Grandfather (round riverbed) rocks in a large fire until they're cherry red. They are then placed into a pit in the lodge and splashed with cedar tea to create the medicinal steam we need. Many of the rocks fracture which we call Grandmothers and then later, these are easily smashed with hammer into a fine powder.

Grandmother rocks are usually discarded since they are not used again in subsequent lodges. For me, this has become a perpetual source of fresh rock dust which I apply to my community garden plots at Hamilton's Gage Park.

Now if I could only get my hands on genuine Hammaker Gravel Grinder!

This wonderful discussion will inspire me to look for local Rock Dust resource within the Maryland, DC and Virginia areas. Can't thank you enough as I'm learning so much through our various discussions.

I purchased rock dust in 50lb. bags. The product is called Agrowinn, and the owner told me that is was better than Azomite because of much lower levels of alumina... I am not an expert in this stuff, but it made sense at the time (plus, Azomite or Gaia Green was not available locally).

Recently, I called a local compost facility, and asked about rock dust. The owner told me they don't specifically market rock dust, but that I was welcome to come and screen it myself.

When I arrived at the facility, it was a large lot with nothing growing on it. I live in the Southern California high desert, and there isn't much humus in the soil. However, there was one pile of volcanic rock (pink) they called "candy stripe." Weeds were  popping up through this pile of rock like crazy -- the only living green thing on this lot.

The owner said they had a problem with weeds there, and I just bit my lip in excitement. Of course, that was the pile I screened, and ended up buying 1 cubic yard of the stuff for $30. He had no idea why I wanted it, and I didn't get into details (he may want to charge me more in the future!)

Needless to say, I have no idea of the mineral content, but I took a clue from mother nature and thought if weeds can grow like crazy in a sandy lot, maybe my 1 acre hobby farm / super garden would as well.

End result is a mixture of glacial rock dust and this volcanic stuff, mined in California near Ventura.

There is much more to this experiment of mine beyond rock dust... I am also doing a deep wood chip bed (Back to Eden style), with a small amount of inoculated biochar. I will be posting my result all year via my blog.

Thanks!

Troy

Hi Troy,

Exciting adventure tracking down rock dust, isn't it? Please do separate plots if possible, one with the product that you mentioned, one with the local source that you found called candy stripe and one with a combination of the two versus a control. Do you think that might be possible? You could get a low-cost scale and measure the weight of the plants.

Please document well and perhaps we can have an article on the website. If you post something on your blog, please put a link to it here or post in general and perhaps write a blog here as well.

William, I'm hoping that you will do something in the realm of urban gardening that you can document and also create an article for us by the end of the summer. Do you think that might be possible?

All the best,

Joanna

Remineralize the Earth

Hi William,

I'm wondering if you did find rock dust for your garden and what the results were for this season?

Best wishes,

Joanna

William A Ellerbe said:

This wonderful discussion will inspire me to look for local Rock Dust resource within the Maryland, DC and Virginia areas. Can't thank you enough as I'm learning so much through our various discussions.

Hi Troy,

Please make sure that all the links to your blog are available to us, that are specific to remineralization, and I am particularly interested in your results with biochar. We have a research project in eastern Massachusetts with rock dust and biochar, looking to find an optimum combination to get the greatest yields and Dr. Tom Goreau will be presenting a paper at the North American Biochar  Symposium at UMass in October:

http://symposium2013.pvbiochar.org

Unfortunately we did have some problems with flooding this year which set us back for our second growing season and  the late harvest data will probably not be available in time for the conference.

Also, please feel welcome to be in touch with me by email.

All the best,

Joanna



Troy Martz said:

I purchased rock dust in 50lb. bags. The product is called Agrowinn, and the owner told me that is was better than Azomite because of much lower levels of alumina... I am not an expert in this stuff, but it made sense at the time (plus, Azomite or Gaia Green was not available locally).

Recently, I called a local compost facility, and asked about rock dust. The owner told me they don't specifically market rock dust, but that I was welcome to come and screen it myself.

When I arrived at the facility, it was a large lot with nothing growing on it. I live in the Southern California high desert, and there isn't much humus in the soil. However, there was one pile of volcanic rock (pink) they called "candy stripe." Weeds were  popping up through this pile of rock like crazy -- the only living green thing on this lot.

The owner said they had a problem with weeds there, and I just bit my lip in excitement. Of course, that was the pile I screened, and ended up buying 1 cubic yard of the stuff for $30. He had no idea why I wanted it, and I didn't get into details (he may want to charge me more in the future!)

Needless to say, I have no idea of the mineral content, but I took a clue from mother nature and thought if weeds can grow like crazy in a sandy lot, maybe my 1 acre hobby farm / super garden would as well.

End result is a mixture of glacial rock dust and this volcanic stuff, mined in California near Ventura.

There is much more to this experiment of mine beyond rock dust... I am also doing a deep wood chip bed (Back to Eden style), with a small amount of inoculated biochar. I will be posting my result all year via my blog.

Thanks!

Troy

Lovely garden! I wonder what local materials are available in your area that could be screened, if they are not already screened into a fine dust? You might be able to find a fine dust from the same riverbed.

Joanna

Thank you for sharing these wonderful photos! I am not aware of this way of grinding rocks and utilizing it and I'm wondering if Native Americans in the past through thousands of years may have done this?

Joanna

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