A different kind of jade
The Wuntho-Banmauk jade deposits represent a geological formation process distinct from Myanmar's more famous Hpakant mining area. These are primary, in-situ deposits where jadeite is found directly within its host rock, not as alluvial boulders washed into riverbeds. The deposits occur as veins, dykes, and lenses embedded within a body of serpentinite, a rock formed by the alteration of Earth's upper mantle material. This entire geological assemblage is part of an ophiolite complex, a slab of ancient oceanic crust and upper mantle thrust onto the continental crust.
The formation is a direct result of tectonic activity along the Sagaing Fault system, a major strike-slip fault that defines the boundary between the Burma microplate and the Sunda Plate. As the Indian Plate subducts beneath the Eurasian Plate, intense pressure and temperature changes occur. In this high-pressure and low-temperature environment, fluids rich in sodium, aluminum, and silicon percolate through fractures and fault zones in the serpentinite. This process, called metasomatism, triggers a chemical reaction that transforms the host serpentinite into jadeite (NaAlSi2O6), the rare and valuable of the two minerals classified as jade. The jadeite forms directly within these fault-related conduits, creating the characteristic dyke-like deposits of the region.
The source of a unique color
While most jadeite is known for green hues, caused by chromium, the Wuntho-Banmauk region is produces lavender jade. The unique coloration is primarily attributed to the presence of manganese (Mn3+) ions substituting for aluminum within the jadeite crystal structure. The specific absorption of light by these manganese ions gives the mineral its purple appearance. The intensity of the color often correlates directly with the concentration of Mn3+ in the stone.
The geological conditions that favor the formation of jadeite also concentrate these trace elements. The metasomatic fluids that transport the primary components of jadeite—sodium and aluminum also carry dissolved elements from the surrounding rocks. The serpentinite host rock and other nearby metamorphic rocks provide the manganese and other trace elements, like titanium or iron, that can influence the final color and quality of the jade. Unlike the massive boulder fields of Hpakant, the jadeite here is extracted directly from the hard rock matrix, making mining operations fundamentally different and often on a smaller scale. The deposits are more sporadic and less concentrated, but the unique colors found here give them distinct gemological value.