Metallica's album Master Of Puppets is the first heavy metal recording chosen for preservation by the Library of Congress due to its historical importance.

The US Government-run library's National Recording Registry each year selects 25 pieces judged to be "culturally, historically or aesthetically significant" and keeps the best-quality originals to safeguard for future generations.

A statement from the library said Master Of Puppets, released in 1986 as the third album by Metallica, "shows the group moving away from its thrash-metal history and reputation and exploring new ideas".

"Thrash, a reaction against the pop metal of the early 1980s, aimed to renew metal by emphasizing speed and aggression," it said, while crediting "Master Of Puppets" with also aiming to "break free of thrash orthodoxy"....