Within a New York Times article titled "Our Ever Green World" one finds the text
Green was changeable, capricious, as uncontrollable as fate, no more to be trusted than a green-skinned goblin or sprite. “From the 16th century on,” Mr. Pastoureau writes, “gaming tables were covered with green baize, the color symbolizing chance, the stakes, the ante, and the money to be won or lost.”
Later, chemists invented far more stable green dyes, including the chromium trioxide ink that put the green in our bank notes beginning in the 1860s. The green ink can’t be destroyed by acid or base or other chemical agent, it’s resistant to fading, and it’s extremely difficult to counterfeit. It’s the perfect backdrop for a Founding Father’s face.
One notes that the pigment to make paper money green is chrome green, which is a chromium (III)
Oxide., Cr2O3. Chromium trioxide, CrO3, is chromium (VI), and is not green.