The claim that Harun had overseen the mines in Adhan was a bit of a misnomer as although he did do all the work, it was under a noble, who took all the glory.
This was one of the reasons behind Alexander's decision to choose Harun as coupled with the man's vast experience, he was also clean, and unconnected to any nobility.
This was a crucial factor for Alexander as he had enormous, super projects in mind, particularly the blast furnace, and secrecy regarding them was paramount.
Thus he needed a man who was both competent and reliable to spearhead them and Harun seemed to fit the bill.
A second reason for choosing Harun was because he hoped that this would encourage others to work even harder, using Harun's status as a precedent to set their goals as they desperately worked to emulate him.
"Mister Harun, I will leave the mines to you. Work hard and soon Adhania will have a new shordar (baron)." Alexander's enticement drew another round of flattery and puffery.