Let's be very clear, "mummy color" is most definitely not the same as a mother color.
Rather, the color "mummy" was made from ground-up Egyptian mummies. Yes, that's right, embalmed humans were made into paint. Mummy brown was used in European art in the 18th and 19th centuries, "from the 1800s until the 1920s"1.
Mummy was a tar-like pigment because of the resins used during the embalming process. These days anything sold as "mummy" is made from less-gruesome alternatives that are mineral in origin rather than organic. The Mummy Brown sold by Natural Pigments, for instance, contains the minerals goethite and hematite.
"Black paint can be made of soot and galls, peach stones and vine twigs or even ivory... But one of the more notorious ingredients in the seventeenth century was bone black, which was said by some to be made from human corpses. [But] in fact it was not black [that] was made from dead human beings. It was brown."1
References:
1. Simon Jennings Artist's Colour Manual, p75.
2. Victoria Finlay, Colour: Travels Through the Paintbox p112.
