Where can I find this in SA?
I'm intrigued by the discussions on the benefits of glacial rock dust in the articles I've been reading. It's such an obscure element though, especially here in Texas where you'd have to special order it and pay for the shipping which is substantial. I don't doubt that adding any rock dust to your soil (except limestone, of course) would be good for mineral and tilth enhancement. Since it is a dust it would be a source of immediately available nutrients for plants but also please consider that it's expensive to mine and ship and is a nonrenewable resource just like oil and peat. Except if we have another major ice age that creates lots more glaciers that create lots more glacial dust. haha.
Anyway, the real reason I'm writing on this subject is because you will have a lot more success finding other beneficial products already available in stores and garden centers so all you have to do is go and get them. Lava sand is a proven material that does the same thing and maybe more and better enchancement to our soils here in Texas. The micronutrients are spectacular, the material is a renewable resource, and it brings exceptional tilth to any soil you have. It even can enhance potting mixes by providing better drainage if you should overwater.
Lastly, use what you have in your kitchen, food waste, egg shells, paper napkins, paper towels, etc and make compost. Talk about a renewable resource, and leaves and grass clippings and a shovel full of any kind of dirt will make the best additive for your garden soil. DH and I create enough kitchen waste to run ten compost bins. We do impose on our neighbors for their lawn waste bags in the summer and add those to our mixtures. They are so happy to have us take it off their hands, they bring it to us and put it in our back yard for us. Compost will neutralize your alkaline soil, attract worms and nourish your plants. Yes it's work to make it, and it takes some time, but it's free and when it comes out of the bin all dark and rich and sweet smelling it's the best thing you can do for your soil.
The only place I have been able to find glacial rock dust is on the internet, in pop-up ads attached to those articles about it's wonderful benefits to the soil. And frankly, the convenience of sales ads linked to "research" articles reeks of someone's get rich quick scheme to me.