I just re-read this whole thread. The term 'sand' is like quicksand, when trying to sort through definitions. Each industry that uses sand puts different labels on the sands sold for their industry. Some have very specific uses. The consumer market makes very little distinction, what ever is cheap gets bagged and a label slapped on. Sometimes the label means something, often it does not.
My approach is to not over-think this. It's not rocket science. (though I know we have a scientists few here)
Think about your purpose.
For orchids in a mixed collection, (emphasis on mixed) you simply want a fine particulate for root hairs and mycorrhizae (if present) to grab on to and increase absorbtion area. Play sand will work fine. Any of the many crushed or mined silica products will work. River sand is ok except for extreemly sensitive plants like some carnivourous plant. Sand is a minor component, no need to worry about particle structure and air voids. 90% of us don't need to read further, it is that simple.
If you are mostly raising terrestrials, like Paphs, and most of your species are calciphiles, crushed limestone, such as is sometimes sold, also crushed granite as in paver's sand also is just fine. Oystershell and crushed dolomite are all very usable. Any combination is fine, I add both oyster shell and play sand to the mix for my calciphiles, like stonei and bellatulum. In a way, this is even simpler than above.
If you are raising sensitive plants, like carnivorous plants & Cypripediums, only the most inert of media can be used. Here you need to look at what is being sold as play sand. If it has a rusty color to it, it may have more iron and other ingredients than you may want. You really need something that is pretty much pure silica quartz. Some play sands are good, sand sold for the outdoor cigarrette ashtrays tends to be very pure white, and cheap, this is pure silica. Those would work fine as a minor component.
But for a carnivorous plant soil or a sand based soil for cypripediums, where the sand is a major component (over 20% of the mix) you need some structure and air voids. Here the sharp sands available at a builders supply house would be helpful. Same place or a machine supply house like Grainger, would sell silica for sand blasting. Here the particle sizes are graded, and you can get very specific size particle. These supply houses are not orientated to the consumer. You will only see them listed under wholesale or manufacturing supply. Designing soils is a really complex topic, wander over to bonsai info on the net and look at the information about inert or inorganic bonsai soils. Be prepared for hundreds of pages on the topic, but much of it is good.
Rose, just south of you on Hwy 12, is McCann Ready Mix and Concrete Supply. You can get sharp builders sand there, also various pure graded silica quartz. (I've used the Wedron 10-40 by Unimin Corp, because I used to get it for free) I think McCann is still in business? If not try the Meyers Material yard at Hwy 41 & Hwy 137 by Great Lakes Naval Base. I think there are Ozinga and maybe a Prairie Ready Mix yard on Hwy 12 also. You could go west on 173 to the Theilen's Quarry west of Richmond, head to the office, don't use the truck entrance. If they are busy, they might not want to make time for you. My name won't help your there.
All these places are commercial / industrial. They usually are open week days only. Avoid the early 6 am to 9 am rush. Get there before 4 pm or they will be closed. Bring a check book, credit card, or cash, with the ability to make some change yourself. They mostly deal with companies on accounts, so they may be awkward in the way they handle cash customers.
When searching for industrial sands check you local listings for
Ready-Mix & Concrete Supply, also Concrete Block & Pre-Cast Supply
Brick, Block & Stone Supply (we have an actual brick yard the next town over from me)
Machine and Tool Supply (for sand blasting aggregates only)
Building Supply (Lumber yards often do not carry sands, but sometimes they do)
Landscape operations, not so much nurseries, but Landscape outfits that do excavation, you want to see earth movers, more than trees in burlap.
Feed Stores, Poultry Supply - I frequently get my crushed granite for my bonsai soils at the local feed store. Ask for poultry grit. I prefer the Turkey Grit, because the granite is the same size as seedling bark, 1/4 to 1/2 inch. Grower grit is finer, 1/16 to 1/4 and Starter grit is very fine, less than 1/8th for chicks. Pigeon grit is crushed granite with both oystershell and some anise in it to attract the pigeons to peck, around 1/8 to 1/4 inch.
Look for the word Supply, there are Ready-mix plants that do not sell anything other than ready-mix on the truck.
Hope these ideas help.
Leo
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