What metal is the Voyager Golden Record mainly made of?

The Voyager Golden Record is mainly made of copper.

Each Voyager spacecraft carries a 12-inch copper phonograph disc designed as a time capsule for any distant civilization that might find it. The disc contains sounds, music, spoken greetings, and images encoded in analog form, presenting information about Earth and its inhabitants.

Copper was not left exposed: the disc was plated first with nickel and then with gold. This layered construction improves durability and helps protect the recording from corrosion during its potentially immense journey through interstellar space. The record’s protective cover is aluminum and includes a sample of uranium-238.

The gold plating explains the record’s famous nickname, but it does not mean the disc is made primarily of gold. Nickel, titanium, and aluminum are present in the record assembly or its cover, yet copper is the base metal of the playable disc.