What's the price in the pottery store. I buy all my white silica sand from dust to course white pretty cheap at a local concrete supply. All are about $7 for 50 pounds. Silica sand seems to cure harder than any other sand as well. Great stuff. A little super plastisizer helps it set even harder with zero cracks. A bit of lime helps give it that clay texture as well.

Silica = silicon = silicon dioxide. It's extremely common in the earth's crust in silica-rich rocks such as obsidian, granite, and sandstone. Feldspar and quartz are the most significant silicate minerals. Silicon also alloys with a variety of metals, including iron, aluminum, copper, nickel, manganese. It's often used in foods as an anti-caking agent, so it isn't likely to harm you unless you breathe the dust, which can put you at risk for respiratory issues like silicosis. Wear a mask, as you should when you are working with sphagnum moss, perlite, pine bark, and other soil products that contain dust you could inhale. Moistening it as soon as it's feasible in soils also considerably reduces any risk. Al

I think silica is the same as crystals from what I can see. I did use them for a number of years. They worked the best of any cat litter I had ever used. However, I did read and hear from the vet that they are not very good for your cats and that it is bad for their lungs. Two of mine have lung issues that may or may not be from this litter, but I have since switched to the worlds best cat litter.

Although this is not the greatest of situations, it's not something that a one time exposure is going to be dangerous. Not like asbestos. This is something that just this year became enough of a concern that OSHA has decided to regulate airborn free floating silica. I'm about to turn 61 and although not as well as I should, I'm still breathing after 38 years in the trade (but that also includes 35 years of smoking, too). Bottom line-- if this were an ongoing thing where you were breathing it in, in mass quantities, I'd be concerned. I don't think this is serious enough where you have to worry about professionally abating the silica, or scrubbing your ventilation system. I WOULD, however, do as thorough a job of cleaning as you can. Maybe use a vacuum with a hepa filter on it (Home Depot has them for their Rigid shop vacs).