X is for xenotime

So far we've had a crystal structure starting with every letter of the alphabet, except one. Xenotime is not some kind of bizarre extra-terrestrial timekeeping system, but is in fact a mineral. Ironically, it was supposed to be spelled with a "k", after the ancient Greek kenós (κενός) which means "vain", but an early misprint replaced the "k" with an "x", which stuck. The main component of xenotime is yttrium orthophosphate. It also contains relatively high levels of uranium and thorium impurities, which makes it very useful for U-Th-Pb isotopic dating of sedimentary rocks.

What does it look like?

A xenotime crystal. Source: http://www.mindat.org

Yttrium orthophosphate, the main component of xenotime. Yttrium atoms are shown in green, phosphorus in purple, and oxygen in red. Image generated using the VESTA (Visualisation for Electronic and STructural Analysis) software http://jp-minerals.org/vesta/en/

Where did the structure come from?

The structure was determined by M. Strada and G. Schwendimann in 1934, and can be found in the Crystallography Open Database (#1011143).

Tags: crystal structure   collagen   biological   radiometric dating   yttrium   mineral