Sonata movement (fragment) in G minor, K. 312
von Wolfgang Amadeus Mozart
Mozart’s Sonata movement for piano in G minor (K. 312) is a late, unfinished keyboard fragment, usually dated to Vienna around 1790. What survives suggests the opening stretches of a full sonata-allegro movement—dramatic in character, but breaking off before any recapitulation can arrive.
What Is Known
Only a single, incomplete movement for solo piano survives under the Köchel number K. 312, in G minor. It is commonly placed in Mozart’s late Vienna years (often c. 1790), when the composer was 34, though the basis for so exact a date is largely source- and paper-based rather than supported by any explicit inscription. The autograph itself breaks off abruptly, mid-system, leaving the movement without a finished second half and without a cadence that would close the structure in the tonic.[1]
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Descriptions of the surviving text agree that what remains corresponds to the exposition and development of a sonata movement in 3/4 time.[1] Modern catalog listings and circulating editions typically label the piece simply Allegro (K. 312/590d), reflecting both its fragmentary state and the lack of an authoritative, complete sonata to which it could belong.[2]
Musical Content
Within the surviving pages, Mozart writes in a tense G-minor idiom that recalls the heightened rhetoric of his other late works in minor keys, yet filtered through a keyboard texture that can turn quickly from incisive, forte gesture to more lightly articulated passagework. The manuscript suggests a movement conceived in sonata-allegro form (exposition followed by development), but the break in the autograph means that any planned return (recapitulation) and tonal resolution must remain a matter of inference rather than documentation.[1]
[1] MozartDocuments.org — document page that summarizes the K. 312 fragment (autograph breaks off; surviving portion described as exposition + development; 3/4 time; discusses dating issues).
[2] IMSLP — work page for Allegro in G minor, K. 312/590d (score availability; common title and catalog cross-reference).