Wiktionary
n. A mixture of solid and metallic oxide-bearing impurity that is a waste product of bauxite refinement.
Wikipedia
Red mud or red sludge is a waste product generated in the industrial production of aluminium. With about 77 million tons of this hazardous material produced annually, red mud is one of the most important disposal problems in the mining industry.
Usage examples of "red mud".
Behind us Marrakech, with its nine kilometres of red mud walls and its flat-roofed houses dotted with storks' nests, lay sprawled out in the clear morning sunlight, a sleepy pattern of red and brown and white.
And they reaped the bloody harvest so the ground beneath their feet turned to red mud, and the river flowed brightly.
It was a city of square houses of red mud-brick, all heaped on each other like a tumbled pile of boxes.
And last week he came home from his route with red mud on his shoes, when it hadn’.
Vaylo clearly remembered laughing with Jon Grubber and Mas-gro Faa as they'd bludgeoned a dozen Trenchlander cindermen along the red mud banks of the Choke.
The company commander kicked at the brick-red mud in the bottom of the trench.