| Abstract: | Of the many petrophysical properties such as acoustic velocity, dielectric constant, electrical resistivity, etc., the widest variation is shown by magnetic responses. Susceptibilities commonly range over 4 orders of magnitude between different lithic samples. Thus, magnetic properties show great potential for the characterization, provenance-determination, thermal history, and treatment of stone tools and masonry. In order of increasing complexity and decreasing value to the archaeologist, we recommend low-field susceptibility, saturation remanence, hysteresis ratios, isothermal remanence acquisition, and alternating field demagnetization of a saturation remanence. The natural remanence (NRM) is rarely of any value in characterizing artifacts. The physical basis for this discrimination is the nature of the magnetic minerals, their abundance and distribution through the sample, and, for remanence-bearing minerals, their domain structure, crystallographic perfection, and grain-size. These characteristics may be changed in distinctive ways by cultural effects such as percussion or fire, and surface conditions such as frost action, forest fires, or subsequent weathering. © 1998 John Wiley & Sons, Inc. |
