substantival possessive pronouns     German English     feminine masculine neutral     Nominative meine meiner meines mine   Genitive not used * not used * not used * of mine   Dative meiner meinem meinem to mine   Accusative meine meinen meines mine               Nominative meine meine meine mine   Genitive not used not used not used of mine   Dative meinen meinen meinen to mine   Accusative meine meine meine mine

* In common language the Genitive of the substantival possessive pronoun is not used. There is another form of a possessive that could be used (der meinige, die meinige, das meinige), but it sounds really antiquated. If you want to form a Genitive of meine it is mostly done like in English.

Das ist der Schlüssel von meinem (Auto etc.). = This is the key of mine. (my car etc.)

If absolutely necessary one could also use meinige, it just isn't common to do so :

Das ist der Schlüssel des meinigen. = This is the key of mine.