When diaspore reaches gem grade, it refracts brilliant light due to its extremely high fire, and also has strong pleochroism—unlike other color-changing gemstones that change from one single color to another, it can refract multiple colors at the same time, the most significant being a mixture of red and green. No wonder the locals call it "Five Colors." Roland hadn't thought of it when he heard Barov's introduction before, but the moment he saw it with his own eyes, he immediately associated it with this stone.

In addition, when diaspore loses water, it turns into corundum... and the gem grade of corundum is the famous ruby and sapphire. The latter is more famous than the former.

However, what excited him was not the gemstone itself.

"What about the residue dug out of the mine?" After a long time, the prince closed the wooden box and asked excitedly.

"You mean... the gravel dug out when opening the mine?"

"That's right, not just stones, but also mud. How did you dispose of these wastes?"

"After being transported out, they are piled up at the foot of the mountain," Denver didn't seem to understand the meaning of the prince's question. "Your Highness, please rest assured, we have carefully screened these ores. Either the quality is too poor, or they are broken during the mining process and cannot be polished into gemstones. The screening process is handled by the most experienced veterans in the family, and there is no possibility of omission."

"You're wrong," Roland shook his head with a smile. "Those things... may be the real 'treasure'."

"What?" Denver was stunned, and the expressions of the others looked quite surprised, as if they couldn't associate mud with treasure at all.

But he couldn't explain this matter—because even steelmaking is difficult in this era, let alone extracting elemental aluminum.

The main component of diaspore is aluminum oxide. As a by-product of bauxite, its discovery very likely means that aluminum is enriched in this area, and soil and rocks can be used as raw materials for aluminum smelting. As the most abundant metallic element in the earth, aluminum reserves are higher than iron and are almost everywhere. In other words, Lucia can decompose trace amounts of aluminum from any stone dug out of the ground—but it is not cost-effective for industrial extraction. Therefore, only places with aluminum enrichment have exploitation value.

For example, this cave in front of him.

Roland called Peiluo aside and asked in a low voice, "How has the Kelian family managed the gemstone mine for the past two hundred years? I mean... how should the lords of each generation pay them?"

"I found it in the account books left by Osmond. Ryan. The way to pay is very simple, that is, the Kelian family can choose a box of secondary gems from the collected gems as a reward every year, which is basically the same as weighing wheat." Peiluo explained, "The box is about a palm long and wide, and half a palm deep. As long as the lid can be closed, you can put in as many as you can. Of course, the most rare gemstones must be handed over to the lord."

"That is to say, the two family collections he just gave me are not the best?"

"In terms of texture, they are indeed the best. He wouldn't dare to lie to you on this point, but you also know that gemstones are always more expensive the larger they are."

"You have also received gifts from him, right?" Roland looked at the eldest son of the Honeysuckle family with interest.

"Uh..." the latter responded awkwardly, "Yes, Your Highness, I will give the gemstones to you when I go back."

"Keep it, I don't care about this," the prince said indifferently, "I'm just curious, who guarantees that this reward is accurate? What if the family secretly takes more during the mining process? Unless you turn the mansion upside down, you can't find out this kind of thing, right?"

"Every batch of ore will be supervised when it is transported out of the cave and screened, and even if the Kelian family steals, they will not do it too obviously—this is a relationship of mutual restraint. They are afraid of being discovered by the lord and being severely punished, and the lord can't find so many people who know the mine well," Peiluo paused, "Besides, even if you replace it with your own people, who can guarantee that they won't steal?"

"I see," Roland nodded, "Then let's continue to do it according to this rule. But in addition to the Five-Color Stone, I also want the crushed stone and mud that are dug out. After I go back, I will formulate a preliminary collection plan for you, and implement it according to the requirements above first."

"Your Highness, is this mud... really more valuable than gemstones?"

"It depends on whose hands it is in," the prince replied.

What is aluminum? Its uses are countless. The characteristics of low density and corrosion resistance alone support half the sky of industrial production, and it is also an indispensable key material for aerospace technology. It is true that aluminum smelting is a troublesome task, and the amount of electricity required by the electrolytic equipment is astronomical for Neverwinter City, but with Lucia, a batch can always be accumulated. At that time, some weapons and equipment that are no less than miracles in this era are also expected—such as large airships.

Roland originally planned to focus on the development of the two iron mines, but it seems that the plan needs to be adjusted slightly now.

……

After inspecting the remaining two mines and a salt well, he returned to the castle, and it was completely dark.

After dinner, Roland couldn't wait to pull out paper and pen and start planning the utilization of new resources.

The first is the steam engine.

Whether it is mine drainage, hauling, or brine extraction from salt wells, steam engines can double the efficiency. The Maple Leaf and Wild Rose families have now been destroyed. He plans to transfer a group of skilled workers from the North Slope Mine and recruit a large number of workers in the Changge District to start operating the two new iron mines first. The ore can be hauled back to the Border District for smelting. The gemstone mine needs to wait for Lucia to go to Changge to test the aluminum content in each tunnel before arranging the next mining direction.

Another focus is the salt well.

Close to what Roland expected, in addition to using steam engines to pump water to increase production, the remaining work to obtain snow-white refined salt is impurity removal. Considering the complex geological composition, he decided to take a tube of brine from each well back to the Border District and hand it over to the chief alchemist Caimo. Streer to study the specific impurity removal steps, and then set up a factory on the spot to mass produce edible salt.

Of course, the salt industry, like grain, should also be operated exclusively by the City Hall. The salt wells of the Elk and Honeysuckle families can obtain technical support from Neverwinter City, but the refined salt produced must be sold to the City Hall at the prescribed market price, and must not be sold to other places privately for profit. If a large amount of refined salt can be obtained at a low price, it will undoubtedly open up a new trade route for Neverwinter City.

Roland hopes that all this will be on the right track after the Tefico zhèngquan collapses. (。)