100 000 Mark Duisburger Kupferhütte

Duisburger Kupferhütte was a major copper smelting operation in the Ruhr, and like hundreds of German industrial firms during the hyperinflation of 1923, it issued its own emergency currency — Notgeld — to pay workers when the Reichsbank simply could not supply enough physical banknotes to meet payroll. The 100,000 Mark denomination places this squarely in the middle phase of the inflation spiral, before denominations climbed into the billions and trillions later that same year.

Factory-issued Notgeld of this type was typically redeemable only at the issuing company's cashier window, which kept it functionally local and limited counterfeiting incentives.