Hairs from mummies discovered in the west China Taklamakan desert are investigated by NanoSIMS, ToF-SIMS, Auger and TEM. Intra-medullar accumulations of calcium and phosphorus are described. The present study is an attempt to understand the significance of these accumulations. Their possible exogenous or endogenous origin is debated. Moreover, TEM revealed a particular nature of the accumulation that decorates a fibrilar structure of the medullar. To what extent did molecular control govern the particle growth and does such an accumulation represent a step toward the mineralization of the keratinized fiber? (c) 2008 Elsevier B.V. All rights reserved.