 At Freiberg, he met a number of men who were to prove important to him in his later career, including Spaniard Manuel del Rio, who became director of the School of Mines the crown established in Mexico; Christian Leopold von Buch, who became a regional geologist; and, most importantly, Karl Freiesleben, who became Humboldt's tutor and close friend.During this period, his brother Wilhelm married, but Alexander did not attend the nuptials.Humboldt graduated from the Freiberg School of Mines in 1792 and was appointed to a Prussian government position in the Department of Mines as an inspector in Bayreuth and the Fichtel mountains.