The Madison County Sheriff's Office says it identified the explosive material found near Beaver Dick Park.
A man originally found the mixture Sunday. He threw it in water, and it blew up in his face. The man was not seriously hurt. He reported the incident Monday.
The sheriff's office said Tuesday it was a homemade concoction of easily obtained chemicals. They were intended to explode after hitting water.
Detectives believe whoever made the material was playing with the mixture and left some behind.
The Idaho Falls Bomb Team was called in to help dispose of the remaining material Monday afternoon.