The mine that Lu Zhen had previously found had at least a thousand low-grade qi; however, they could barely be exchanged for a middle-stage qi stone, which was unlikely because no one would exchange for something of higher value for a lower grade of Qi stone because the higher the grade of the Qi stone, the purer the qi, and the quantity of the Qi contained in the stone also increases to at least a hundred in quantity as well as quality.
Middle-grade Qi stone was at least a thousand times more effective than a low-grade one, not to mention the speed of refining. Since the middle-grade stone is only one, it could be absorbed easily with the dense Qi inside, helping the martial artist strengthen their bodies as well as condensing Qi, which was invaluable to second-stage martial artists.
