Which pigment was made by walling cattle in a shed and feeding them only mango leaves?

Indian yellow, a deep transparent gold used in Mughal miniatures and later by European painters, made from the dried urine of cattle fed on mango leaves and little else. The leaves are mildly toxic; the animals were reportedly malnourished and short-lived, and the practice was banned in India around 1908.

The account rests almost entirely on one letter, written in 1883 by a civil servant reporting what he had been told about a village in Bihar, and no one has produced a second independent source or found the village. Chemists have made the pigment from the urine of cattle fed mango leaves, so the chemistry works; whether the industry existed as described, and how widespread it was, is genuinely uncertain.

Historic pigments are full of this. Mummy brown was made from ground Egyptian mummies and was used by real painters into the twentieth century - one buried his tube in the garden on learning what was in it. Scheele's green was arsenic and is a plausible contributor to a great many Victorian deaths from wallpaper. Emerald green was used both as a paint and as an insecticide.