Mineralogy Adventure in Cambodia: Looking for Topaz in Takeo Province

Museum mineralogists Paula Piilonen and Glenn Poirier are in Cambodia, looking for minerals relevant to their research. Follow along on their first trip to Takeo province, near Vietnam.

After a few days of acclimatization and overcoming jet lag in Phnom Penh, my colleague Glenn Poirier and I set out on our first mineralogical adventure of this year’s field season in Cambodia. We are planning a day trip to the little-known topaz, aquamarine (beryl) and smokey quartz mines in Takeo province, about 90 km south of Phnom Penh, close to the border with Vietnam.

A person stands on a rocky outcrop with stone stairs.

The top of Phnum Bayong Kao, a 310 metre-tall mountain that is the destination of our first mineralogical adventure of this year’s Cambodia field season. Image: Paula Piilonen © Canadian Museum of Nature

Populated, forested and agricultural areas seen from elevation.

A view from the top of Phnum Bayong Kao. Image: Paula Piilonen © Canadian Museum of Nature

Our driver, Mr. Sin, was with us last year and invaluable because he was able to translate and communicate to local miners and gem dealers what we were after. The province is not on the main tourist route and English is almost non-existent in the towns and villages. The few tourists who do venture off the beaten path and visit Takeo are often only interested in purchasing the cut gems, whereas we are interested in rough mineral specimens for our collection and research. This requires a slightly more detailed conversation with dealers to convince them that yes, we actually do want the not-so-pretty stuff that no one else wants!

A cut gem and a natural crystal.

It take some discussions to convince the dealers that we are looking for the not-so-pretty stuff that no one else wants, like the rough smokey quartz from Takeo, Cambodia, that you can see here (right) beside a cut specimen. Both specimens are from the museum’s collection. Image: Michael Bainbridge © Michael Bainbridge

Discussions with a gem dealer in the morning market in Kirivong town revealed to us that mining was currently at a standstill from the absence of water in the river—as in Ratanakiri province, water is used to wash the soil and weathered rock in order to expose and concentrate the gem material. No water = no mining. However, this didn’t hinder our plans to explore and collect specimens to shed light on the geology and mineralogy of the deposits.

The mines are located at the base of Phnum Bayong Kao, a 310 metre-tall mountain with an Angkorian-age temple at the top, Wat Bayong Kao. As in other parts of Cambodia, mining in Takeo is done by hand—digging ditches into the soil and stream beds to collect loose minerals. There is no hard-rock mining with explosives and machines here.

A person stands amid stone walls and paving.

Prasat Bayong Kao, an Angkorian-age temple. Image: Paula Piilonen © Canadian Museum of Nature

A man sits in front of statues and offerings.

A monk at Prasat Bayong Kao. Image: Paula Piilonen © Canadian Museum of Nature

As a result, the production of the region has greatly diminished in the last few years as the “easy” deposits are mined out. In order to expose more gem-bearing pockets, mechanical, hard-rock mining methods would have to be employed.

We chose to hike to the top in the relative “cool” of the morning, doing geology on the way down (it’s much easier to carry rocks down a mountain than up!). The mountain itself is a very coarse-grained quartz-and-feldspar granite with cavities containing well-formed smokey quartz and topaz crystals.

A granite outcrop.

Granite containing the topaz, smokey quartz and aquamarine gem deposit. The gem minerals are found in cavities within the granite. Image: Paula Piilonen © Canadian Museum of Nature

Unfortunately, extracting minerals from the rock proved to be a futile effort with the limited equipment that we were carrying (rock hammers and a small chisel). After sampling the granite, our driver took us to a lunch spot at the base of the mountain with a convenient gem market. This gave us the chance to browse the rough and cut smokey quartz, topaz and aquamarine from the deposit, as well as to purchase a number of other hand samples containing additional mineral species (tourmaline) for our research.

Two crystals and a cut gem.

Rough and cut topaz from Takeo, Cambodia, from the museum’s collection. Image: Michael Bainbridge © Michael Bainbridge

It was also a great learning (and shopping!) experience for the three non-geologists who had tagged along with us for the day—everyone came back to Phnom Penh happy. As the saying goes, a bad day in the field is always better than a good day in the office. But this was definitely a good day in the field.

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.

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