A Visual Encyclopedia of the Periodic Table

91

Transition Metals

Osmium

Os

76

Osmium is the densest of all naturally

occurring elements: 250 ml (8.5 fl oz) of this

metal (in its liquid form) weighs 5.5 kg (12 lb).

This rare element is found in the ore osmiridium.

Pure osmium reacts with oxygen in the air to

form a poisonous oxide, so the metal is used safely

by combining it with other elements or alloys. A

red osmium oxide stains cells so they can be seen

clearly under a powerful microscope, while a

black oxide powder allows fingerprints to be

revealed in crime investigations. A hard osmium

alloy is used in fountain pen nibs.

Forms Uses

Osmium oxide is

used to highlight

objects inside a cell.

Black osmium

oxide powder

clings to oily

fingerprints.

The nib of this pen moves smoothly

because of its hardy osmium alloy.

Fountain pen

Transmission

electron microscope

(TEM) image

Finger print

powder in use

The needle of

this old record

player is made

of osmium.

Record player

The pure form

is hard but

shatters easily.

This is a natural

alloy of osmium

and iridium.

76 76 114

State: Solid

Discovery: 1803

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