Why was Alexander von Humboldt invited to Russia and Siberia in 1829?

In 1829, Alexander von Humboldt was invited to visit Russia and Siberia at the initiative of the Russian minister of finance, Count Yegor Kankrin.1

The primary purpose of the invitation was for Humboldt to serve as an adviser to the Russian government regarding the techniques and organization of mining, specifically to inspect the gold and platinum mines located in the Ural Mountains.1

While the expedition provided significant scientific value through his geographical, geological, and meteorological observations of previously unknown regions in Central Asia, Humboldt was required to pledge that he would not comment on the political situation of the country, as he was a guest of the tsar and traveled under the supervision of an official guard.1