$OS
Osmium (Os) is the densest naturally occurring element on Earth, a rare, hard, and bluish-white platinum-group metal discovered in 1803. With a density of \(22.61 \text{g/cm}^3\), it is used in specialized high-wear applications, such as fountain pen tips, electrical contacts, and scientific instruments. It is also used as a catalyst and in electron microscopy staining, although it is highly toxic when oxidized, and extremely expensive.
