#Mercury is nasty. Don't vote for it in the #MinCup23. Give it up for #Sepiolite, which may be a little weird, but it isn't trying to ruin your nervous system or screw up your geochronology...

In uranium-lead geochronology, lead has four isotopes (atoms with the same number of protons, but different numbers of neutrons and hence slightly different atomic masses). These are ²⁰⁴Pb, ²⁰⁶Pb, ²⁰⁷Pb and ²⁰⁸Pb. All but ²⁰⁴Pb are produced by the radioactive decay of uranium and thorium and hence we use those for dating #minerals. ²⁰⁴Pb is primordial meaning whatever ²⁰⁴Pb there is has been hanging around since before the Solar System formed. It tells us how much 'common' lead was already in the mineral when it formed and needs to be corrected for in our age dating calculations.

Wretched mercury also has several isotopes, one of them is ²⁰⁴Hg and is very, *very* close in atomic mass to ²⁰⁴Pb. So close that in most mass spectrometers ²⁰⁴Hg will look identical to ²⁰⁴Pb and pretty much screw up your common lead calculation. And because mercury is an insidiously foul pox of an element, it can get into everything and stays there. Some laboratories, because of an earlier dalliance with mercury diffusion vacuum pumps (another horror story), have had to be decommissioned because even decades later they could still see traces of mercury in every measurement.

So please don't vote for mercury. It doesn't deserve your attention. Go #TeamSepiolite