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Fluorite by Hearth – Canadian Museum of Nature Weblog


As we climb larger and better up the mountain alongside a worn path by the dense forest, I’m wondering if it’s doable for us to soften within the 40°C Cambodian warmth. It’s an arduous hike, however our environment and the minerals we’ve come to see make the journey value it.

Museum scientists hiking down a dusty trail on Phnom Bayong in Takeo province, Cambodia.
Climbing down Phnom Bayong. Picture: Paula Piilonen © Canadian Museum of Nature

We’ve come to the south of Cambodia, alongside the Vietnamese border, to check Phnom (mount) Bayong, a granodiorite mountain that hosts pegmatites containing beryl (var. aquamarine), topaz, smoky quartz and fluorite. After two hours of slogging our method up by the forest, we arrive on the miner’s present workings. Excessive above the city of Kirivong, the miners are utilizing conventional strategies to interrupt aside the granodiorite that makes up Phnom Bayong, to extract fluorite from veins to promote to gem sellers, vacationers and locals.

Fluorite—CaF2—is wanted by mineral collectors, lapidary artists and the bigger mineral trade. It happens in all kinds of colors and types, the most typical of that are inexperienced or purple cubes; nevertheless, blue, pink, yellow and colourless fluorite in octahedra and uncommon dodecahedra also can happen. This range of color, kind and behavior provides fluorite nice aesthetics and makes it a preferred mineral amongst collectors.

Commercially referred to as “fluorspar,” fluorite has been used as a flux within the smelting of iron ore because the 1500s, and extra not too long ago within the manufacturing of aluminum and metal. It is usually used to supply hydrogen fluoride and within the manufacture of glasses and enamels.

Fluorite was first mined in Canada from deposits at St. Lawrence on the southeast coast of the Burin Peninsula in Newfoundland. Found in 1843 and commencing manufacturing in 1928, the St. Lawrence deposits had been the biggest identified in North America on the time. Veins and lenses of fluorite kilometers lengthy and as much as 10 metres thick had been mined by hand underneath back-breaking situations, at first in floor trenches and later underground. Operations expanded extensively after World Conflict II because the demand for aluminum and metal rose. By the Seventies, elevated competitors from different international locations drove down the value of fluorspar ore. Because of this, operations at St. Lawrence, then owned by ALCAN, had been in the end shut down. In 2018, Canada Fluorspar Inc. (CFI) put forth a proposal to renew mining operations.

A miner works underground in harsh conditions at the St. Lawrence Fluorspar mine during the 1970s.
St. Lawrence miner, circa 1970. Picture: © Heritage Newfoundland & Labrador.
A photograph of the head frame and mill at the Director Mine, St. Lawrence Fluorspar mine, taken around 1960.
Head body and mill on the Director Mine, St. Lawrence Fluorspar Mine, circa 1960. Picture: © Heritage Newfoundland & Labrador.

No powered gear is used to mine the fluorite at Phnom Bayong—hauling mills up the mountainside isn’t sensible. The employees revert to a centuries-old strategy of fire-setting to crack the rock. Hearth-setting was probably the most fashionable mining strategies till the invention of dynamite by Alfred Nobel in 1866; nevertheless, dynamite is difficult to come back by in Cambodia.

A miner works in a trench to extract fluorite from a vein.
Miner in a trench. Phnom Bayong, Takeo, Cambodia. Picture: Paula Piilonen © Canadian Museum of Nature
A vein of purple and green fluorite within the granodiorite at Phnom Bayong.
Fluorite vein. Phnom Bayong. Picture: Paula Piilonen © Canadian Museum of Nature

The employees minimize down bushes and lay them within the trench. A fireplace is ready and left till it burns itself out. The warmth from the hearth expands the rock, after which it’s quenched with water to create cracks. The damaged rock can then be chiseled and hammered at to reveal a contemporary layer. One other fireplace is ready, and the method continues till the fluorite is reached. It’s laborious work, however the fluorite items may be bought within the gem market on the base of the mountain for more cash than a mean Cambodian makes in a single day.

Logs in a trench are set on fire to expand the rock.
Hearth cracking of the granodiorite. Phnom Bayong. Picture: Paula Piilonen © Canadian Museum of Nature
Mr. Sokphun holds up a large piece of green and purple fluorite from his mine.
Mr. Sokphun, fluorite mine proprietor. Picture: Paula Piilonen © Canadian Museum of Nature

The gem mines at Phnom Bayong are usually not well-known, besides to the locals and some gem sellers. Our analysis within the area, nevertheless, will assist make clear the mineralogy and genesis of the deposits, and assist improve the general geological data of the nation.

Mineralogist Paula Piilonen meeting some of the local dogs while examining mineral samples.
Assembly among the locals on the fluorite mine. Phnom Bayong. Picture: © Sovanny Ly
Paula is holding a small, light-green cube of fluorite that was found in a pegmatite within the granodiorite at Phnom Bayong.
A small (3 cm) inexperienced fluorite dice from a pegmatite within the granodiorite at Phnom Bayong. Picture: Paula Piilonen © Canadian Museum of Nature

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