Announcing the appointment of Jorge Arreaza, 43, in a television broadcast, Maduro recalled that developing mining was part of his emergency plan to reboot the stricken economy.
Arreaza is a son-in-law of Maduro's late predecessor Hugo Chavez, father of the "socialist revolution" that is now floundering in crisis.
Venezuelans are suffering shortages of food and medicine as prices for the country's crucial oil exports have fallen.
Fending off opposition pressure for a vote on removing him from office, Maduro has vowed to rescue the economy by boosting production in the countries' southern mining belt and other sectors.
"Mining is one of the great sources of financing for development for the coming years," he said on Sunday.
The president claimed that Venezuela is in the process of "authenticating what could be the biggest gold reserve in the world."
He says Venezuela also has diamonds, copper, iron and bauxite. His government is looking for investment from countries such as Britain, Canada, China, Russia and South Africa.
Arreaza is a former vice-president and is married to Hugo Chavez's daughter Rosa Virginia Chavez.
Chavez also named a new fisheries and agriculture minister, Gilberto Pinto.
In an earlier reshuffle, he last month named a new vice-president, hardliner Tareck El Aissami.
El Aissami has since been targeted by sanctions from US authorities, who accuse him of drug-trafficking.
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