Water is worth it in very specific locations, because we can build a dam and let the natural shape of the Earth do the heavy lifting. But a dry system, relying

Water is worth it in very specific locations, because we can build a dam and let the natural shape of the Earth do the heavy lifting. But a dry system, relying on weights? There isn't a material that is dense enough to make it worthwhile. Even a boxcar full of granite would need to be orders of magnitude heavier than it is for gravity storage to be economically useful.