You can check out remineralize.org for a primer on the value of rock dusts, there are other resources as well. One thing about these amendments is to get them in bulk if possible. For example, you will see dolomitic lime and gypsum available in 50 pound bags for $10-15, and it is also sold in 5 pound bags for $6-8. Gravel or granite dust may be sold for $1-10 per ton or cubic yard.

It sounds like you are preparing to seed a lawn. You might want to consider planting trees that fix nitrogen in the soil, a vegetable garden, fruits, a mix of grasses that doesn't require fertilizing or watering, or better yet a mix of these things. It may be preferable to have a wide variety of things growing and producing to look at and enjoy rather than a flat patch of monotonous grass, especially one that requires care.

There are also the Organic Lawn Care and Lawn Care forums you can try. I'm sure someone will be glad to recommend a good seed mix and how many times per week to mow, spray, mow, fertilize, mow, mow, mow, spray etc. Good luck.

Does your soil need it? Only a professional soil test can tell you. If not, why waste your money on a maybe sort of thing.

Gypsum helps clays only if the underlying problem is excess sodium. A rather uncommon thing.

Compost, lots and lots of it, repeated every season, is the sought for Silver Bullet.

Its good but just as good as the next Organic treatment. You can find greensand in many Organic fertilizer mixes.

Personally I would only use it if I knew EXACTLY what I needed. Other than that, I use it in a mix with many other Organic products. There is really no one stop fix for your garden unless you are growing a certain flower/tree that requires a certain high level of any one nutrient. I would agree that compost is the key. Other than that, I have heard that green sand helps with clay soil.

Greensand can provide a number of necessary micro nutrients to your soil, and then your plants providing you have enough organic matter in that soil to feed the Soil Food Web that will make them available to the plants. As jean001a stated a good, reliable soil test should indicate whether you need to spend money on greensand, or any other soil amendment, or not but the single most important thing you can do for your soil, and the plants that grow in that soil, is get the level of organic matter into the 6 to 8 percent range.

It is certainly a good amendment for leached soils low in K. I have used it, but never in such a controlled way that I could state exactly what the results were, but that also goes for any and all amendments I have ever used.

Look at item number 221052783709. The price reasonable for 40 pounds. I would like put this in my raised bed. I have sandy soil, but it's bad compacted fine sand. My raised beds have none of the native soil. Sand improves them. I got some horticultural sand on sale in small bags at osh. But, they don't sell it anymore. I would depend on if the sand if fine grained bad or large grained good. Is this a good deal? I don't know, if you have clay I don't know if you want large or small grained sand. I just know that fine grained sand packs down hard as a rock if you don't keep adding tons of compost all the time.

just a note, the seller said it is a really a mixture of clay and minerals, but called sand, so I don't know if that is something that would be helpful or not.

Greensand comes from mineral deposits that once were part of the ocean floor and has a nutrient analysis of 0-0-3 but is known to contain several other micro nutrients. It can be a useful amendment for soils lacking those provided there is an active Soil Food Web to convert them to nutrients plants can use which means you also need sufficient levels of organic matter in the soil.
Concentrate first on getting adequate levels of organic matter in the soil and then test to see if you need to add greensand or anything else. Many people have found that after a few years of getting, and maintaining, adequate levels of organic matter the nutrients are in sufficient, and balanced, supply without spending money on these supplements.

The scoop is it's not sand it's clay, so if you have clay, of course it's not that much clay, it could be of some benefit.
They should call it green clay.

It will arrive as a big lump or maybe a bunch of little lumps that you will have to deal with. If you have ever dealt with trying to blend clay into your soil you will know what I am talking about. It may be nice, but if you can't blend it with your soil you won't get the so called benefits. It may be fun to try out a small bag if you can buy it locally, but ordering a big bag by mail is a bad value. The 40 pounds will be mostly water weight.

All of the Greensand I have purchsed has ben quite dry, very little moisture unlike the compost and "garden soil" I have seen for sale which does have a large percentage of moisture.

I am talking about the one that posted the link for above. It is a cheap price. I might buy a bag today, if I can find a small bag at the local store in san mateo.

Greensand has properties of both sand and clay. The particles are like sand, however, it will absorb moisture from the air like clay. Not all deposits of Glauconite, (Greensand), are the same however, and some contain no K at all, as far as I understand. However, aside from the trace minerals, Greensand is a great source of Fe, which in my opinion, is very important for proper plant growth, and therefore don't really think of it as a micro-nutrient, (I feel the same way about Ca and Mg).