Which precious metal is the densest?

Osmium is the densest precious metal.

It is a hard, brittle, blue-gray element in the platinum group, with the chemical symbol Os and atomic number 76. Its density is about 22.59 grams per cubic centimetre at room temperature, making it slightly denser than iridium and roughly twice as dense as lead.

The difference between osmium and iridium is extremely small. For many years, measurements were not precise enough to establish which metal was denser, and both were described as possible record-holders. Improved crystallographic measurements eventually placed osmium marginally ahead under standard conditions.

Osmium is also unusually rare and difficult to work. It is generally recovered as a by-product of nickel and copper processing rather than mined as a primary metal. Its compounds require care: osmium tetroxide is highly toxic and volatile. Metallic osmium, however, has specialist uses in exceptionally durable alloys, including some electrical contacts and instrument components.