Archaeomineralogy of Taiwan Nephrite: Sourcing Study of Nephritic Artifacts from the Philippines

Abstract

Green-colored nephritic jade artifacts are commonly found in Neolithic archaeological sites in Taiwan and some regions of the Philippines. Nephrite deposits only occur rarely in nature, and it is widely accepted that chemical analysis is required if nephritic artifacts are to be sourced to specific quarries. In order to define the mineralogical character of the Fengtian nephrite in Taiwan, an electron probe micro analysis (EPMA) was carried out on nephrites from this source and others in East Asia and the Pacific region. Seventeen nephrite specimens were analysed, and found to be composed of tremolite-actinolite amphiboles (Mg / [Mg+Fe] less than 0.93) with fibrous texture, and bearing chromian-spinel inclusions with significant amounts of manganese (Mn: up to 9 wt. %) and zinc (Zn: up to 7 wt. %). These chemical characters can be applied to differentiate the Fengtian nephrite from others.An EPMA sourcing study was also applied to a series of green- and white-colored nephritic artifacts excavated from the Philippines. These included nine green nephritic ornaments from the Tabon Caves on Palawan Island, a fragment of a green nephritic bracelet from the Nagsabaran site in the Cagayan Valley, northern Luzon, and four white nephritic adzes from Batangas, southwestern Luzon. The results indicate that there are at least two kinds of nephrite raw material that were used in the Philippines. The green nephrite, used mostly for the ornaments, was derived from the Fengtian deposits in eastern Taiwan. The white nephrite found in many Batangas sites, not of high quality, was only used for tools such as adzes and chisels and may have been acquired from a local Luzon source. Consequently, this study provides some important evidence about interaction between different prehistoric populations across a large area of Island Southeast Asia.