Zinc is a Clue available from Mission 3: The Lost Diamond. There is also a Card Combination.
The clue Zinc was in the diamond that Jean-Baptiste brought from India. The Ekats had somehow taken it during the French Revolution, and cut it to more smaller fragments. They safely stored it in a safe in Russia.
Both this combo and Mission 3: The Lost Diamond unlock Zinc.
- Card 7: Maria Marapao
- Card 24: Lilya Chernova
- Card 35: Hope Diamond
- Card 37: Jean-Baptiste Tavernier
- Card 55: The Golden Fleece
The cutscene shows a vault with the Ekat crest on it that opens. Inside, there is a necklace and lasers. The camera dodges the lasers and zooms in on the diamond on the necklace. The fault turns into a rectangle and turns the screen black. The word 'Zinc' appears in white.
Zinc, also known as spelter, is a metal, and is needed in humans.