In Helaman 13, Samuel the Lamanite says multiple times that the Nephite treasures would become “slippery”, such as in verse 31:
And behold, the time cometh that he curseth your riches, that they become slippery, that ye cannot hold them; and in the days of your poverty ye cannot retain them.
While it may seem odd to a modern audience to describe treasures as being “slippery”, this concept is at home in the ancient world including texts likely known by Israelites.
Kevin Barney comments:
it seems more than coincidental—yet not surprising—that the concept of slippery, disappearing treasures is found both in an Egyptian text known to the ancient Israelites and in the Book of Mormon, a record with cultural, linguistic, and literary roots in the ancient Near East.– Kevin L. Barney, “‘Slippery Treasures’ in the Book of Mormon: A Concept from the Ancient World,” Insights, June 2000, 2.
How would Joseph Smith know about treasure becoming slippery due to the land being cursed?