Arthur realized he was being taught by this master, and he was really excited by this gain. It was his first, really first, time since coming to this world to be taught by someone about it and its secrets. "This energy is neutral, far stronger than both combined. As the mother of all energies, it can supplement any other minor form of energy, giving it huge benefits in less time."
He stopped, and Arthur didn't need him to continue. He already understood the real implications of this ore, and he planned to seriously widen the usages of it, not just using it to build his city.
Also he realized he underestimated the importance of this place. his enemies wouldn't stand still against his interruption to their plans, and the chances for them to send an army to retrieve the mine was pretty high.
So, he decided to instantly order everyone in the city to come here and extract the ore, turning this mine empty in the shortest span of time.
