Chapter 13 Jadeitite and other high-pressure metamorphic rocks from the Jade Mines Belt, Tawmaw area, Kachin State, northern Myanmar

Abstract

The world's largest jade deposit, containing the highest-quality jade, is exposed in the Pharkant-Tawmaw (also spelled Hparkant or Hpakan and Tawhmaw) Jade Mines Belt, northern Myanmar. This belt is located between latitudes 25° and 26° N and longitudes 96° 12′ and 96° 25′ E in the Myitkyina district (Fig. 13.1). The belt extends in a north–south direction, covering an area of c. 1200 km2 (Chhibber 1934 b ). Major jade production sites are located in the Pharkant, Lonkin, Tawmaw, Haungpa and Hwekha areas. In these areas the rock type jadeitite, containing more than 90 vol% of the mineral jadeite, is associated with serpentinites, albitites, low- to medium-grade metamorphic rocks, chlorite schists, garnet–mica schists, graphite schists, glaucophane schists and amphibolites. Fig. 13.1. Geological map of the Jade Mines Belt (JMB) showing the localities mentioned in the text and the location of the samples described. Compiled by Thet Tin Nyunt, modified from Chhibber (1934 a ), Bender (1983), Than Tun (1997) and Thet Tin Nyunt (2009). The Jade Mines area of northern Myanmar is a highly dissected upland, higher in the north than in the south, with ranges of hills forming the Chindwin–Irrawaddy watershed. The main jade area around Tawmaw is situated on a plateau 840 m above sea level. Mountain ranges in the western part of the area rise to 600 m and are covered by dense vegetation. The eastern margin is bounded by the Uru River. The Tawmaw area is characterized by very high rainfall and, due to the tropical climate, the rocks are highly weathered and covered by a reddish-brown soil of thickness a few metres to tens of metres. Fresh samples of jadeite can be collected only from mine sites or from stream courses. In the Tawmaw area jadeitite is quarried from both primary deposits and as …