Rock!

ROCK, as we know it, is primarily a music style that was born in the mid-twenty century. Its impact has derived in the creation of other types of rock such as heavy metal, punk, pop rock and several others. It is popular everywhere so it has become part of the identity of cultures other than the Anglo-Saxon and thus we have Rock in Spanish, in Portuguese, in German and practically in every major language in the world.

But that is ROCK as a noun. The same word also exists as a verb and it has an entirely different meaning. Here is an example:

In order to make her baby sleep, Jill sings a lullaby and rocks the cradle with her hands.

ROCK, a regular verb, is put into Spanish as MECER as long as it is a verb. It is also an adjective if added the –ing form, e.g. a rocking chair (una silla mecedora). 

Of course, there is another meaning for the word Rock as a verb: To Rock also means To be The Best. Curiously with meaning ROCK is rarely used in any other tense but the simple tenses (Simple Present or Simple Past), never in Present Continuous for example. You never say: "I´m rocking!".

ROCK as the music style is not changed when used in Spanish. Simply put, Rock is Rock. However, when ROCK means “a chunk of an undetermined mineral” then we must translate it as ROCA.