@FrankBr05713205 Mike Rowe had someone on his podcast (sorry forgot the name) who was talking about just this issue .. maybe check on his sites to see if there's any info.
@OrevaZSN Rocks shells and sand. While in Egypt, I filled an empty water bottle with sand at the base of Khufu .. at home filled little glass vases and gave them out .. a few said it was the best gift ever - 25 cents per bottle