Textile pseudomorphs, formation

Replacement of Protein and Cellulosic Fibers by Copper Minerals and the Formation of Textile Pseudomorphs... 

Pseudomorphs on a bronze Shang Dynasty halberd (ca. 1300 b.c.) were subjected to mineralogical analysis to determine their structure and composition. X-Ray diffraction, scanning electron microscopy, and energy dispersive analysis of x-rays were used in these analyses. Photomicrographs of pseudomorphs also were studied for fiber, yam, and fabric formations that give evidence of textiles. A model describing the process of silk pseudomorph formation was proposed. 

Two categories of pseudomorphic textile fabric formations were identified. One, the yam type, moves in and out of the second, the fabric type. At least six areas of the latter are apparent. 

Questions that remain concerning the process of silk fabric pseudomorph formation on the bronze halberd will be resolved with further study of pseudomorphic formations, particularly on objects whose provenance is documented precisely. A more complete description of the microenvironment of the buried objects as well as a quantitative analysis of the mineral composition of the pseudomorphs is necessary for the development of equations for the chemical equilibria involved. Future work is planned to study pseudomorphs as mineralogical structures and pseudomorphs as evidence of textiles. This work includes examination of two additional Shang bronze objects currently on loan to one of the authors. 

As a form of direct fabric evidence, the physical shapes of textile fabric pseudomorphs have been studied to identify fiber type and yam and fabric construction. Pseudomorphs of paired filaments in mineralized fabric formations found on Shang-period bronze weapons were determined to be replaced silk (I, 2) S-and Z-twisted silk staple yarn pseudomorphs were identified as well as fabric constructions, including float yams and a ribbed weave. 

In addition to the analysis of physical structural characteristics of textile fabric pseudomorphs, chemical information has been obtained. On bronze and copper artifacts, the pseudomorphs are composed of malachite, tenorite, and cuprite (I, 2), the formation of which probably requires moist conditions, a corrosive metal, and optimum fiber-metal contact (I). Trace elements in their structure vary from object to object and site to site (1-3), but the relationship of these elements and the fiber, metal, and soil composition is not yet known. 

Little published information exists about textile fabric pseudomorphs. For the most part, those interested in the phenomenon have been concerned with the pseudomorph as textile evidence rather than with the process of its formation. There is no established methodology for examining the pseudomorph either as mineral or as textile. 

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