A complex salt found in dry lake beds of Egypt. Originally an ingredient of ceramic glazes. It has the following percentage composition: sodium carbonate 4.9, sodium bicarbonate 12.6, sodium chloride 30.6, sodium sulfate 20.6, silica 10, calcium carbonate 2, magnesium carbonate 1.9, alumina 0.7, iron oxide 0.3, water 4.7, and organic matter 11.7.