Bastnäsite

In short

Bastnäsite is a carbonate-fluoride mineral, honey-yellow to reddish brown, that contains rare earth elements such as cerium, lanthanum and yttrium. It mostly forms in carbonatites, a rare kind of igneous rock. Together with monazite it is one of the two largest sources of cerium and the other light rare earth elements. In Türkiye it occurs at the Kızılcaören deposit in Beylikova, Eskişehir.

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How to recognise it

1. 1

   It is honey-yellow to reddish brown, with a glassy or greasy lustre, usually as tabular or short hexagonal crystals; the streak is white.

2. 2

   Its hardness is 4–5 (a steel knife scratches it, but it cannot scratch quartz). With a specific gravity of about 5 it feels distinctly heavier than a piece of calcite or fluorite of the same size.

3. 3

   It is hard to tell by eye: it is easily confused with other rare earth carbonate minerals, and a sure identification needs laboratory analysis.

4. 4

   At mines it is usually found together with fluorite, baryte and calcite.

Myths and misconceptions

• MythRare earth elements are called “rare” because there is very little of them in the Earth's crust.

  FactMost of them are actually plentiful: cerium is the 25th most abundant element in the crust and is more common than copper. They are called “rare” because they are scattered thinly through rocks, deposits of workable concentration are few, and they are hard to separate from one another.

• Myth694 million tonnes of rare earth elements were found in Eskişehir.

  Fact694 million tonnes is the tonnage of ore rock announced in July 2022; the share of rare earths in it is far below one per cent (news reports give 0.2–0.3%). If that figure is right, the amount of rare earths is a few million tonnes, not hundreds of millions, and how much of it could be mined economically is a separate question that has to be worked out.

• MythRare earth elements are elements found in “earth”, meaning soil.

  FactHere “earth” is the old chemical name for oxides. These elements are not found in farm soil but in rocks, in minerals such as bastnäsite and monazite.

Did you know?

Where is it found?

• Bastnäs mine, Riddarhyttan, Västmanland, Sweden · Type localityThe mineral is named after this old iron and copper mine; the element cerium was found in minerals from here in 1803 and lanthanum in 1839. Bastnäsite was first described in 1838 by the Swedish chemist Wilhelm Hisinger.
• Mountain Pass, California, USA · Major depositA carbonatite about 1.4 billion years old whose main ore mineral is bastnäsite. It was found in 1949 during a search for uranium and was the world's main source of lanthanides from the 1960s to the 1980s.
• Bayan Obo, Inner Mongolia, China · Major depositA huge iron, rare earth and niobium deposit containing bastnäsite and monazite; found in 1927 as an iron deposit, its rare earth minerals were recognised in 1936.
• Fen Complex, Telemark, Norway · Known localityA carbonatite complex about 539 million years old (Cambrian); Wikipedia lists it among bastnäsite occurrences.
• Gakara, Bujumbura, Burundi · Known localityAbout 20 km south-southeast of Bujumbura; narrow veins in the Kibaran fold belt hold mostly bastnäsite with some monazite. Mining was suspended in 2021.
• Zagi Mountain, Peshawar–Khyber area, Pakistan · Known localityA collectors' locality famous for transparent honey-coloured bastnäsite crystals, which have appeared on the mineral market since the late 1990s.
• Kızılcaören, Beylikova, Eskişehir, Türkiye · Major depositOre veins of bastnäsite, fluorite and baryte associated with a carbonatite-bearing complex that formed about 25–24 million years ago. It is Türkiye's main rare earth deposit; for the size claimed in the 2022 announcement, see the Türkiye section on this page.

Locations are approximate to protect sites. Red dots mark places in Türkiye. Open in the big map →