Mogok, Myanmar, is praised as the ‘gemstone capital’ for producing top-quality ruby. The author paid a visit to gemstone mines in the region late last year to gain a first-hand account of the mining activities of ruby and other coloured gemstones.
Joanne Chan
In mid-December 2015, Dr Edward Liu led a Hong Kong study mission to Mogok to understand the current state of the local gemstone mining practice and the environment. The 18-member group includes jewellery trade practitioners, gemmologists as well as gemstone and mineral lovers from other industries. I set off on 18 December with great excitement. By midnight we arrived in Bangkok, Thailand and stayed at a hotel nearby to catch the flight next day to Mandalay, Myanmar.
Upon arrival in Mandalay, we exchanged the local currency and applied for visas to enter Mogok. In the afternoon we stopped by a local jade market that sold mostly fei cui of unequal qualities. Medium- and low-priced green fei cui cabochons were a common scene.
On the next day, we rode on a 4WD for six hours before reaching the Mogok mining area. We took the old route; the highway is narrow and built along the rugged mountain terrain. The Mogok mines are located in the province of Mandalay, about 200km to the northeast of the city. Since the military government took control of Myanmar in the 60s, the area had adopted a closed-door policy that prohibited foreigners’ entry. The area only reopened in 2012 but visitors must be led by a local tourist guide permit holder and apply for a visa to access the Mogok mines. After passing the visa inspection point in the area, we entered the mines. The six-hour journey was bumpy and exhausting. In the end we were met by a sign reading ‘Welcome to Ruby Land’. We finally reached the mysterious Mogok.
Mid-December does not fall into the rainy season in Mogok. It is therefore suitable for mine visit. There was considerable temperature difference between day and night. While the temperature was seven degree Celsius in the morning and at night, it could be as high as 20"J in the afternoon. Sunrise time was about 6:30AM when the fog was dense. As temperature rose during the day, the fog dissipated and a blue sky was revealed.
Some of the mines in Mogok are operated by the government while some others are co-operated by the government and private enterprises. The geological features of Mogok are complex, with different mines having their own characteristics and rock types which can be divided into primary and secondary deposits. Rocks of primary deposits are mainly composed of metamorphic gneiss containing scapolite and garnet; granite containing pyroxene, amphibole and feldspar; pegmatite containing gemstones such as rock crystal, topaz, tourmaline and beryl; ultrabasic rocks containing peridot; metamorphic marble containing ruby and spinel, etc. Secondary deposits are layers of gravel that are mostly found in deep valley and the two sides of mountains. Commonly found gemstones include ruby, spinel, rock crystal, tourmaline, feldspar, etc.
During our five-day stay in Mogok, we have visited a number of mining areas including the Lin Yaung Chi mine and the Shwe Pyi Aye mine in the east. The two primary deposits of corundum were first mined in 1975 and 1995 respectively. The Pyaung Guang Village in the north is a primary deposit of peridot. The Chaung Gyi mine in the northeast is a primary and secondary deposit of spinel and sapphire. In the west there are Ruby Primary mine, Kadoketart mine and Thet Naing Aung mine, which are all primary deposits of ruby. The Kyautpyattat mine and the Baw Lone Gyi Htay Paing mine are primary deposits of ruby and spinel. The Sakangyi mine is a primary pegmatite deposit of topaz, crystal and aquamarine.
Since each mine has its own characteristics, different mining methods are therefore employed.
•Kadoketart mine: Miners drill holes down to the earth and excavate gemstones with simple tools of cables and pulleys.
•Ruby Primary mine and Baw Lone Gyi Htay Paing mine: Miners make tunnels parallel to the ground on the side of the mountain, and transport mineral rocks to the ground with trolleys.
•Lin Yaung Chi mine: An opencast mining method; miners blast the rock with explosives and then wash the gravel with powerful jets of water to collect gemstones.
•Kadoketart mine and Kyautpyattat mine: A cave mining method; miners climb into the caves according to their formation. This mining method is very dangerous but could best preserve the appearance of the rough gemstone.
•Alluvial mining is commonly adopted in secondary deposits by combining the flow of the stream and the old sieving method.
Currently, the Myanmar government has imposed environmental regulations on the mining industry. Environmental protection work such as tree plantation must be carried out after the mine is closed in order to restore the land. Besides, mining waste will be passed to the women in the villages, who could own the gemstones obtained from sieving.
Various coloured gemstones are produced in Mogok. Their respective properties are listed below:
•Ruby: Production from primary deposits including the Kadoketart mine and the Thet Naing Aung mine are of the best quality.
•Sapphire: Good clarity and beautiful colours. Many special sapphires are also produced, including star sapphire, trapiche sapphire and a paragenetic gemstone of sapphire and spinel.
•Spinel: Formed in metamorphic marble with beautiful colours and perfect crystal structure
•Peridot: The crystal structure is flatter and more elongated compared to peridot produced in other countries. The most common colour is yellowish green.
•Tourmaline: With radiating crystals resembling grapes and triangular coloured growth zones on crystal structure.
•Amber: With inclusions such as mosquitoes, small worms, ants and plants
•Painite: Only found in Myanmar so far
•Hackmanite: a type of sodalite which is in purple or pink
Apart from the above gemstones, apatite, diopside, fluorite, kornerupine, moonstone, rock crystal, scapolite, topaz and zircon can also be found in Mogok.
Besides visiting mines, we also had a chance to witness the heat treatment process of spinel. Very traditional practices were adopted: the sample was put inside a bottle sealed with clay. It was heated in the furnace to 1,200"J. After 20 minutes of heating, it was cooled down for 10 minutes. The gemstone was then soaked in red oil for several seconds and the entire treatment is done.
As for heat treatment of ruby, it requires a temperature of 1,800"J, ten to 15 minutes of heating, twenty minutes of cooling and soaking in red oil for several seconds.
In Mogok, the gemstone marketplace is rather primitive. As far as we saw, transactions were carried out at tea stalls or in open areas with parasols, tables and chairs where sat some buyers who were waiting for suppliers. Most merchandise is rough or cut gemstones of lower grades. Sellers often charge very high prices as much as 10 to 20 times of the market prices. It takes time to bargain. Only patient and experienced buyers are able to make a good deal.
The short mission has significantly enriched our knowledge. Despite the tough journey, it is a precious opportunity to understand the environment of the main mining areas of Mogok and the characteristics and mining methods of different mines, not to mention to take a closer look at gemstone heat treatment. I would like to take this opportunity to thank Dr Edward Liu for his nice arrangement.
Joanne Chan is the chief gemmologist of the Hong Kong Jade & Stone Laboratory Ltd.
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