Element 44 in our International Year of the Periodic Table series is ruthenium. This element finds uses in electronics, fountain pens, and in some fingerprinting techniques.
‘Iridium’ fountain pen nibs are so called because they used to be fashioned from iridium, but these days that’s no longer the case. Present day fountain pen nibs are more likely to be topped with ruthenium, with other platinum group metals such as rhodium also being used.
Ruthenium tetroxide is used to expose latent fingerprints (fingerprints left on surfaces). Fats in the fingerprint transform the ruthenium tetroxide into black-brown ruthenium dioxide, making them visible. There’s more on the science behind fingerprint detection in this graphic.
Remember, you can keep track of all of the previous entries in this series on the site here, or on the Royal Society of Chemistry’s dedicated page.