Greensand: What is it?

During my time searching online, learning about soil, I have encountered the term 'greensand' quite a few times but haven't seen a post on Permies about it. I figured it was about time to change that so here we are! Please feel free to comment your experiences and thoughts on greensand as I am far from an expert on the stuff. I am collecting my thoughts here in this thread and we will see where it goes from here.



Greensand

What is it?

Greensand is generally considered to be glauconite, a marine sediment that contains a variety of trace minerals, silica, and potassium. It is a sand like soil amendment that can help promote drainage in soils. It is considered a long lasting slow release fertilizer of potash and phosphate. The weathering of greensand has been noted to increase the cation exchange capacity in soils by a few online articles. Greensand is utilized in water filtration applications due to it's ability to soften hard water and remove a variety of contaminates. Greensand is viewed as a soil conditioner due to its ability to tighten loose soils and loosen tight soils.

Greensand is produced through mining of deposits and is not considered renewable.

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Yep. They use greensand to remove iron from water. I heard people mixing it with the soil for gardens. Not sure what the reasoning is. That'd be interesting

My first thought is that might be an indicator for gold mining.

Do you have greensand on your property?

Are there gold deposits in your state or area?

Also it can be used to condition the soil due to the mineral content.

Is there any connection between this substance and the green-sand aluminum casting I did in high school metal shop? (Quick googling didn't turn anything up, but I don't know enough about either context to hazard much of a guess of my own.)

Christopher Weeks wrote:Is there any connection between this substance and the green-sand aluminum casting I did in high school metal shop? (Quick googling didn't turn anything up, but I don't know enough about either context to hazard much of a guess of my own.)

Hey there! I've got some experience with casting/molding - They are similar materials, but the words DO mean different things, in the different contexts.
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Green Sand the Soil Amendment is SPECIFICALLY green-tinted glauconite (a mineral with the texture of sand) and any clay, with other trace minerals. It's called 'Green' because the color is literally green.

Green Sand the Sand-Casting material is any type of finely-sifted sand, mixed with bentonite clay, and just enough water added that it sticks together and can catch fine details. It's called 'Green' because it's got moisture, like plant greens have moisture, or green wood has moisture.  It is not actually colored green.

--
Basically: The Soil Amendment is very particular about having green sand in it, while the Sand-Casting material is very particular about having a good sand-clay-water ratio.

I have a greensand water filter to deal with extreme levels of iron in my well water. It somehow absorbs the iron and then it rinses it out with a lil bit of potassium permangante, which readies the greensand to pickup more iron. Beats using a salt softener like the previous owners, says I.

I have never gardened with it. Just couldn't resist shooting my mouth off, hahaah.

I use greensand as a soil amendment in my liquid garden fertilizer, which I also use to inoculate biochar.

Never could get greensand here in FL so I went different ways early on. Kelp in the beginning until it got so expensive, then Azomite ever since.

This is from a truly excellent source of soil amendments.
Everything I've bought from them has been high quality, and they are organic farmers, so whatever they talk about is from hands on experience.

https://www.7springsfarm.com/blogs/news/greensand-why-dont-we-have-it-why-dont-you-need-it

Perhaps this might be interesting? It's my go-to-site on many subjects

https://www.gardenmyths.com/should-gardeners-use-greensand-fertilizer/

It is “metabasalt.” Basalt rock that was heated and pressured for millions of years.

Has calcium, magnesium, iron. 2,4,4%

The large particles will also help break up clay.

For garden, 5-10lbs per 100 sqft
for trees, 1-2lbs per inch of trunk

I personally do not use because it is expensive, heavy, and i do not till my clay, but rather tarp and no till transplant on top of compost.

https://permies.com/t/278274/Paramagnetic-Soil-Amendments-Big-List#2922515

I posted here Paramagnetic.

Greensand, a natural mineral rich in glauconite, is an effective soil amendment. It improves soil structure, enhances water retention, and slowly releases potassium and micronutrients like iron and magnesium. Apply 5-10 lbs per 100 sq ft, mixing into the top 6 inches of soil. Best for sandy or nutrient-poor soils, it promotes long-term fertility without rapid nutrient leaching. Use sparingly to avoid over-application, as benefits accumulate over time.

I like to toss in BioC or Zeolite with it to buffer it.