~~~ in Mylar, is by having too many pages in an album... especially if any of the chips are not perfectly flat; which is not always easily visible without the "glass test" to see if there may be any slight warps.

The mishap usually happens at shows and during trading session when someone will flip a stack of weighted pages onto a page that might have a warped chip when closing the album... or roughly dropping that album onto another album which may have a slightly warped chip on the first page. It doesn't take much to crack a chip which is slightly warped or even perfectly flat if the albums are not handled correctly while flipping the pages.