I found this, but still not sure what "Mercury" is.
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https://www.sunoco.com/about-us/heritage/
The mining business attracted Sun in 1941, when Sun formed the Cordero Mining Company in Nevada to supply mercury for Sunoco motor oils. The metal proved vital during the World War II effort. So, too, did Sun Shipbuilding and Dry Dock Company – which turned out 40% of all wartime tankers built or reconverted.