The chemical removal of manganese dioxide coatings from fossil bones from the Cradle of Humankind, South Africa : research letter

• Published in: South African journal of science Vol. 101; no. 1; pp. 101 - 103
• Main Authors: Cukrowska, E.M., McCarthy, T.S., Pole, S., Backwell, L., Steininger, C.
• Format: Journal Article
• Language: English
• Published: Academy of Science for South Africa (ASSAf) 01.01.2005
• ISSN: 0038-2353; 1996-7489

Many fossil bones from the dolomitic caves in the Cradle of Humankind are covered by brownish-black coatings of manganese dioxide and smaller amounts of iron oxide. This obscures fine details on bone surfaces, making their identification and interpretation by palaeontologists and archaeologists difficult or impossible. The use of acids to remove the coating is undesirable because of the risk of damage to the bone surfaces. We have developed a novel method which selectively removes the coating without damaging the bone. The method is based on the use of hydrogen peroxide as a reducing agent, which converts iron and manganese to more soluble forms. The procedure is inexpensive, effective, environmentally benign and does not alter the bone surface. It is particularly useful in revealing bone surface modifications, especially those that can reveal evidence of early human behaviour.