Lesson plan
Polycrase
Polycrase or polycrase-(Y) is a black or brown metallic complex uranium yttrium oxide mineral with the chemical formula . It is amorphous. It has a Mohs hardness of 5 to 6 and a specific gravity of 5. It is radioactive due to its uranium content (around 6%). It occurs in granitic pegmatites. Polycrase forms a continuous series with the niobium rich rare earth oxide euxenite. It was first described in 1870 at Rasvåg on the island of Hidra, south of the town of Flekkefjord, Norway. It is found in Sweden, Norway, and the United States.
Article summary
Polycrase or polycrase-(Y) is a black or brown metallic complex uranium yttrium oxide mineral with the chemical formula . It is amorphous. It has a Mohs hardness of 5 to 6 and a specific gravity of 5. It is radioactive due to its uranium content (around 6%). It occurs in granitic pegmatites. Polycrase forms a continuous series with the niobium rich rare earth oxide euxenite. It was first described in 1870 at Rasvåg on the island of Hidra, south of the town of Flekkefjord, Norway. It is found in Sweden, Norway, and the United States.
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
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