Jade in Myanmar

Douglas J.Kirwin

Ivanhoe Mines Ltd., Vancouver

Jade has played an important cultural and economic role in Chinese society for thousands of years. The commodity actually comprises two distinct minerals: nephrite, which is microcrystalline mixtures of tremolite-actinolite amphibole, and jadeitite, a dense rock composed mostly of jadeitic pyroxene. Since Neolithic times most of the production has been from nephrite, while during the last few centuries “imperial jade”, or jadeite has been almost exclusively sourced from northern Myanmar. Research by Harlow et al.,(2007) demonstrates that jadeitite crystallizes from primary fluids as vein type deposits which are generated during subduction of oceanic crust and serpentinization of peridotites. There are 15 recorded jadeitite occurrences around the globe, and these primary deposits are typically very small shear-hosted veins or lenses. The main production of jadeitite is from alluvial deposits within ultramafic terrains, e.g. the Hpakan-Tawmaw district in northern Mynamar. Geological mapping in British colonial times conducted by Chhibber (1934) described tracts of jadeitite-bearing conglomerate terraces with an areal extent of approximately 100 square kilometers. Some of these conglomerate units have thicknesses in excess of 200 meters. The source for the jadeitite boulders are eroded upthrust serpentinised ultramafic blocks adjacent to the conglomerates.

Jadeitite occurs as several color varieties, depending on trace element impurities. The emerald green color which characterizes the highly sought after “Imperial Jade”, is due to the presence of kosmochlor (a sodium chrome silicate). An attractive mauve variety is a result of the presence of manganese. The most common colors are pale to dark green caused by iron derived from an augite component. This is marketed as “Utility Jade”. Jadeitite boulders from Myanmar have a brown to black weathered surface composed of ferrihydroxides, thought to be caused by chemical reactions with the host conglomerate matrix. This makes exploration and quality evaluation extremely difficult. Potential buyers for high quality material risk fortunes on boulders with indications of imperial quality. The gambling aspect of this is somewhat reduced by grinding small windows into the opaque surface around the uncut boulder for indications of quality and value. The main evaluation criteria for uncut jadeitite are color, translucence, texture, size and, to some extent, locality. The criteria used for carved ornamental jadeite are much more sophisticated and complex, and often is dependent on the history of the specific item.

Extensive numerous opencast jadeitite mines currently are located in the Hpakan region in Kachin state, northern Myanmar. The scale of previous and existing mines involves removal and processing of hundreds of millions of metric tonnes from a patchwork of government issued mining leases. The operations are now highly mechanized, utilizing fleets of large capacity excavators. Recovery of the jadeitite boulders on the other hand, is a labor intensive hand sorting process. The selected jadeitite boulders are then graded and sent to Yangon for marketing. There are three to four government-run gem auctions held annually in Yangon where 90% of revenue is from jade sales. The auctions, held over a period of a week or more, attract hundreds of buyers, most of whom are Chinese from Taiwan, Singapore, Hong Kong and elsewhere in mainland China. It is difficult to determine the value of gross sales, however the figures are well in excess of hundreds of millions of U. S. dollars annually. The prices for quality jadeitite, like most other mineral commodities, have risen dramatically of the past two years, largely fuelled by the demand from east and central Asia, including the Indian sub-continent.