Chromium had a certain chance of occurring alongside lead ore, forming chromian lead ore. It could also occur alongside iron ore, forming chromite. The ore in Xingang Commandery consisted mainly of a massive magnetite deposit, but it also contained some associated lead and silver ore.
In other words, the mine in Xingang Commandery contained not only iron, but also silver, lead, and now even chromium!
In fact, this was quite common. Nature generally did not produce minerals containing only a single element. Most were associated ores. When determining what kind of mine a deposit was, people only had to look at which mineral component was most abundant. As for associated ores, a single mine might contain eighty or a hundred associated minerals, and there was nothing strange about that.
Luo Chong could say with certainty that the magnetite in Xingang Commandery contained many other minerals as well. It was just that, with the Han Tribe's current level of chemistry, they had no way to separate them.
And even if they did separate them, they had no technology capable of identifying what metals they were.
This situation had actually appeared at the mint on Lake Heart Island long ago. However, the mint was located deep in the marshes and had always been kept under tight secrecy. On top of that, they had never paid much attention to the phenomenon, which was why the news had only surfaced now.
From the very beginning, when these people smelted lead ore, lead's melting point was extremely low—only two or three hundred degrees—while chromium's melting point was more than 1,800 degrees, around two hundred degrees higher than iron's. As a result, whenever ore was fed into the lead furnace, the molten lead quickly flowed out, while the associated chromium ore was discharged directly as slag.