Searching for Zircon in the Wild, Wild East of Cambodia

As I stand in the pock-marked field, watching the miners and their families working in the red dirt under white tarps, I realize that this is unlike any mine I have visited before. Underground silver mines in Kongsberg, Norway; open-pit silver mines in New Mexico, U.S.A.; larvikite quarries that removed entire mountain-tops in southern Norway; underground and open-pit nickel–copper mines in Sudbury, Ontario; potash mines in Saskatchewan—all of these are large-scale operations that require massive machinery and thousands of employees.

Three men sit beside a pile of earth, while another stands nearby.

Searching for zircon crystals in the weathered basalt at Phum Throm, Ratanakiri province, Cambodia. Image: Paula Piilonen © Canadian Museum of Nature

In front of me, covering no more than three acres, 100 Khmer miners and their families are mining the weathered red rock at Phum Throm with no more than a trowel, bucket and their hands, in search of Cambodia’s newest gem stone: zircon (ZrSiO4).

Four people stand in front of a stone building overgrown by the roots of a tree.

Ralph Rowe, Paula Piilonen, Glenn Poirier and Andy McDonald at the famous Tomb Raider temple, Ta Phrom, Siem Reap province, Cambodia. Image: Paula Piilonen © Canadian Museum of Nature

We’ve come to the wild, wild east of Cambodia—Ratanakiri province near the Laos and Vietnam borders—to visit these zircon mines and collect samples for scientific study. By examining the chemistry of the zircon, we will be able to determine their origins and say something about the part of the Earth’s mantle in which they formed.

Traveling overland from Thailand, our adventurous and intrepid group of mineralogists—Glenn Poirier and Ralph Rowe, both scientists at the Canadian Museum of Nature, and Andy McDonald from Laurentian University—meet up with our guide extraordinaire, Vutha On, and driver, Mr. Pon, in the capital city of Cambodia, Phnom Penh, for our two-day overland trip up to Ratanakiri province.

It’s not a journey for the faint of heart (or stomach!)—900 km in a van over bumpy, pot-holed, unpaved roads leads us into the far northeast of the country where old-growth rainforests still stand, deep-fried tarantula is a staple and farang (foreigners) are few and far between.

A woman bends over a table where she uses tweezers to pick through a pile of gems.

Sorting faceted sapphires at World of Sapphire, Chanthaburi, Thailand. Image: Paula Piilonen © Canadian Museum of Nature

Thailand has long been known for its gem mining—it has been the world’s top producer of sapphires and rubies (two varieties of the mineral corundum Al2O3) since the early 1900s. The area around Chanthaburi is particularly famous, having been mined since the 1400s.

The gems occur in weathered alkaline basalts which have been reduced in the tropical environment to a red soil-like material called laterite. Miners simply sieve the weathered rock and pull out pieces of gem material. No underground mining and blasting here—all the work is done by bulldozer and washing by hand.

A large pit of reddish dirt containing mining equipment.

Sapphire mining operation at Khao Ploi Waen, near Chanthaburi, Thailand. Image: Paula Piilonen © Canadian Museum of Nature

But geology knows no boundaries—”no passport required”, as the saying goes—and the same alkaline basalts that occur in the province of Chanthaburi-Trat, Thailand, also occur in the western (Pailin) and eastern (Ratanakiri) provinces of Cambodia.

By geological standards, these basalts are babies—toddlers really—only 1 million to 24 million years old. But the gems they host are among the best in the world, including the zircons we are here to study.

Digging with Pick and Shovel

A man winches a bucket of earth from a narrow hole in the ground.

Zircon mining by hand at Phum Throm, Ratanakiri province, Cambodia. Image: Paula Piilonen © Canadian Museum of Nature

Back at Phum Throm, without the money to buy bulldozers, miners dig 10-metre-deep holes in the laterite by hand, down which they climb using elbows and knees as support. At the bottom of the hole, loose rock is scooped into a bucket that is hauled to the surface on a rope. At the surface, miners search through the material by hand and extract the precious zircon crystals.

A man in a stream pans for minerals.

Zircon miner cleaning a bucket of mud from one of the holes at the Bo Loei mining area, Ratanakiri province, Cambodia. Image: Paula Piilonen © Canadian Museum of Nature

As we walk through the mining area, we approach individual miners and, after an introduction and translation by Vutha, are shown what they have collected for the day. Small containers are produced from pockets and their contents spilled onto laterite-stained palms for our inspection.

A hand holding some small coloured stones.

Bright orange, pink and red zircons extracted from one bucket of mud in Bo Loei, Ratanakiri province, Cambodia. Image: Paula Piilonen © Canadian Museum of Nature

The miners save all the zircons they collect, but they are primarily in search of gem-quality material (free of inclusions and fractures), which fetches the highest prices.

As mineralogists (not gemmologists), inclusions and fractures are interesting, and so we haggle for second-rate material from the miners. For $5 or $10 USD, everyone is happy—we acquire small bags of zircon crystals for research and the miners profit more than they would by selling in the market in Ban Lung.

A man at a table displays a box of blue stones.

Mr. Pross, mine owner and gem trader, showing off large heat-treated and cut blue zircons in Ban Lung, Ratanakiri province, Cambodia. Image: Paula Piilonen © Canadian Museum of Nature

With Vutha as our guide and translator, we are able to visit five mining areas in Ratanakiri province and purchase samples for our research project. But the experience is more than just science—it’s cultural and historical, a chance to interact with minority Khmers and learn about their way of living in a part of the country that is changing rapidly.

Natural resources in Cambodia abound, and it is only recently that they have begun to be exploited on a large scale. Deforestation in this part of the country is rampant: old-growth hardwood is being logged and rubber trees are planted in their place. Dam construction along the majestic Mekong River threatens natural habitats throughout Cambodia. Mining for zircon occurs on a small scale, but international exploration companies have recently been searching for other commodities (gold, silver, nickel, zinc, lead) nearby.

A wooden crate holding three pigs sticks out from the bumper of the van to which it is tied, while a man attends cargo tied to the roof.

The local taxi in Ban Lung, Ratanakiri province, Cambodia—pigs and all! Image: Paula Piilonen © Canadian Museum of Nature

Cambodia is a country that is just coming to grips with its long history of violence and colonialism, with a people who are desperate to put the past behind them, move into the 21st century and begin to make their place and their own way in South-East Asia. Taking responsibility for their own natural resources—forests, water and mineral resources—is part of this process. When people are asked about Cambodia, two things come to mind: Angkor Wat and the Khmer Rouge. With awareness and careful management of its resources, hopefully we can add Cambodia’s natural beauty to that list.

About Paula Piilonen

A mineralogist with the Research Division at the Canadian Museum of Nature.
This entry was posted in Fieldwork, Research, Rocks and minerals and tagged , , . Bookmark the permalink.

3 Responses to Searching for Zircon in the Wild, Wild East of Cambodia

  1. Blair & Jennifer Campbell says:

    WOW!! You get around. Sounds like it’s exciting to be a geologist today

  2. Pingback: What’s in a Colour? On the Trail of Zircons in Cambodia | Canadian Museum of Nature – Blog

  3. Pingback: Rubber Trees and Zircon Mining in Cambodia—All in a Day’s Work | Canadian Museum of Nature – Blog

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