Silica dust and asbestos are two examples.
Asbestos is far and away a superior refractory, both in price and utility.
No one but workers in an asbestos mine were ever injured by it. Thanks to some very successful lawsuits, i can no longer get asbestos in any form. And as a bonus, people in general are frightened to death of it, as though it were radioactive. Seems like sand is headed for the same fate. We will soon need to go to the beach and collect our own, as companies will be afraid to sell it.