· Use of Magnetite as an Ore of Iron. Most of the iron ore mined today is a banded sedimentary rock known as taconite that contains a mixture of magnetite, hematite, and chert. Once considered a waste material, taconite became an important ore after higher grade deposits were depleted. Today's commercial taconites contain 25 to 30% iron by weight.
It was often used with martial arts. Today, stone balls still exist with iron balls replaced by the more popular steel balls. People greatly interested to build strength and dexterity would start with 2 balls and increase the speed or the number of balls they could work with. There are methods and techniques to go beyond 5 balls in one hand.