A Mystery of History
A Jade and Gold Assemblage from Jincun
This jade and gold assemblage from Jincun is part of a magnificent group of burial objects from the royal lineage of the Eastern Zhou (509–314 BCE). Since the piece (F1930.27) entered the collection of the Freer Gallery in 1930 (fig. 1), it has been deemed one of the finest examples of jade and gold work of the Zhou dynasty. When it was accessioned into the museum’s collection, the assemblage was thought to be a pectoral worn around the neck. In light of archaeological finds starting in China in the 1980s, scholars began contemplating whether the configuration of jades attached to a gold chain was historically accurate. A technical study of the materials, conducted by a conservation scientist at the Freer, has led to a reassessment.
In 1928 heavy rain exposed the top of a tomb at Jincun, the capital of the Eastern Zhou dynasty about twenty kilometers northeast of present-day Luoyang, Henan province (fig. 2). Bishop W. C. White was living near Jincun at that time, and he carefully observed and charted the tombs and their contents. White examined and documented the jade and gold assemblage shortly after it was unearthed at Jincun in an unauthorized excavation by local farmers that began in 1929. According to White, the gold chain was fragmentary when it was excavated. Art dealer C. T. Loo in New York purchased it for the Freer Gallery in 1930. Questions about the arrangement of jades on the chain were voiced from the time it was first described.
Individual elements of the assemblage, which consists of ten jade pendants and beads attached with gold wire to a gold chain, were subjected to technical study. Janet Douglas, a conservation scientist in the Department of Conservation and Scientific Research at the Freer Gallery of Art and Arthur M. Sackler Gallery, undertook the study to determine whether the evidence suggests the jade elements and the gold wire belonged together as a group in antiquity, and if they were buried near one another in the tomb in Jincun.
The jade material of the ten beads and plaques looks quite similar. It is a very fine-grained, homogenous nephrite that ranges from light yellowish green to beige in color and is free of mineral inclusions. This nephrite material is also similar to other objects now in the Freer’s collection that are also thought to have been unearthed at Jincun. C. T. Loo, a Chinese art dealer who years earlier worked closely with Charles Lang Freer, described this jade material from Jincun: “Jades, representing the finest quality of material, sharp carving, light delicate yellowish color, with clear translucency when looked at through the light, and high polished surface.”
Analysis by non-invasive x-ray fluorescence spectrometry (XRF) shows that the ten jades are similar in composition, with only a small amount of variation in the major oxides and slight variation in the minor oxides. All are nephrite (tremolite – actinolite, Ca2Mg5Si8O22(OH)2), more specifically low-iron tremolite (iron < 1.00 wt. %), with minor traces of chromium (0.02 to 0.03 wt.%), manganese (0.02 to 0.04 wt.%), and nickel below the XRF detection limits.
Douglas examined surface encrustations from the burial environment to determine whether they were consistent and typical of other jades from Jincun. Red encrustations were found in small patches on several of the jades. These encrustations were later identified as cinnabar (mercuric sulfide) by detection of mercury and sulfur using XRF. Five of the jades have impressions left from contact with textile or wood. Since these markings would be difficult to produce artificially, their presence supports the idea that the jades had been buried in a tomb environment for several centuries.
To determine if the jades had been buried in close proximity, Douglas used scanning electron microscopy to study small soil samples taken from the jades. The soil was found to be similar to loess, a fine-grained, aeolian (or dust-like) sediment known to occur in Henan province. All ten jades have similar particle types and distributions of soil deposits, with each consisting primarily of rounded, colorless quartz grains and fine, beige clay particles, both of which are typical of loess deposits in northern China.
Douglas found the nephrite material to be visually and compositionally similar. The alteration and surface encrustations indicate the jades were likely buried together in the same or at least similar tomb environment.
Gold wiresfig. 4), but in fact, it is a double loop-in-loop chain constructed from wire loops (fig. 5). The individual wires that form the chain are block-twisted. This process, which dates to ancient times, starts with a craftsman hammering gold into thin sheets. Next, each sheet is cut into strips or rods that are repeatedly twisted, stretched, and then rolled between two hard, flat surfaces to flatten the spiraled wire. Short lengths of wire were soldered into loops and squeezed into a flattened “bow-tie” shape. In a double loop-in-loop chain such as this, folded loops are threaded together so that two loops are fed through each loop to create a dense chain structure with a squarish cross-section. This process is important to understand because, as Douglas discovered, some of the gold attachment wires are original chain loops that were removed and cut for reuse. Someone probably did this around 1930, shortly after the assemblage was unearthed in Jincun in 1929 and before it entered the Freer collection.
To better understand the configuration of these pieces, Douglas studied the gold wires of the chain and how the jades were attached to the chain. In this way she determined which gold wires were original to the chain and which, if any, were added at a later date. She removed twelve of the gold attachment wires for the jades and examined them with scanning electron microscopy (SEM) with energy-dispersive x-ray analysis. (The results are summarized here.) Wire diameter measurements were obtained using the SEM, and the metal composition was determined semi-quantitatively for gold, silver, and copper.
Four groups of the gold wire were established based on composition and wire diameter (fig. 6). The first group (shown in purple) includes those wires determined to be original to the chain because they were found to be similar to a removed loop from the chain. The average diameter of the wires is 0.79 mm. Corrosion in the burial environment probably caused the surface pitting evident on the loops. Douglas used stereomicroscopy to study the length and bent shapes of the attachment wires. Through her examination, she determined those particular wires are loops that had been removed from the chain and cut to attach the jade plaques and beads to it. In some cases the wires still retain fresh cuts at their ends. The use of the block-twisting method to form the wire resulted in variable thicknesses with helical creases along the length of the wire.
The second group includes one wire (shown in green) that was added during a conservation treatment at the Freer Gallery of Art in 1968. That type of wire is composed of pure gold with traces of copper.
Two wires in the third group (shown in blue) have a low percent of silver and no copper, and they have a larger diameter of approximately 1.04 mm. The surface of these wires is relatively clean without adhered soil particles. These two wires hold the assemblage closed where a clasp would be expected.
The fourth group includes two wires (shown in red) that are similar compositionally to the first group of original wires but have a smaller diameter (approximately 0.68 mm). No significant amounts of adhered soil were present on their surfaces. These wires are located where the long bead holds the group of three plaques to the chain.
Unlike the first group of wires formed through block-twisting, the other three groups were formed through the modern method of drawing, in which the wire is thinned and lengthened by pulling it through a series of drawing dies (or holes). This process normally creates wire of uniform thickness with longitudinal ridges along its length. The physical characteristics of ancient block-twisted wire and drawn wire can clearly be seen using SEM (fig. 7).
Based on this technical study of the assemblage, Douglas determined that the individual jades and gold chain are genuine, but the combination may have been a fabrication dating to the late 1920s or early 1930s. The jades were attached with cut chain loops and, in some cases, newer drawn gold wire. This beautiful but curious assemblage has now been reinterpreted to be a gold chain and ten jades, and not a complete pectoral as originally thought. Although their exact role in the tomb is forever lost, this unusual object still represents the graceful workmanship in jade and gold that flourished in Jincun during the Eastern Zhou dynasty.
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