The Survival Committee had set up a law called the Resource Act. The mines discovered within Dragon City by Dragon Citizens were shared treasure that belonged to the entire civilization and had to be used for the grand cause of Earth conquering the Other World.
The first people who discovered a spirit energy ley line had the right to mine it first. They could form their own groups to mine it or give the right to mining organizations with great power so that they could earn high transfer fees.
Also, there was an unspoken rule.
All people who discovered a spirit energy ley line could pick a crystal with the highest purity, the best looks, and the most spirit energy from the mine as a souvenir.
Based on the types of crystals, the size of that "one" piece would also differ. To retain its value, it was enough to make the mine explorers so motivated that they would search for mines wave after wave without regard for their own safety.