All the chords built on other notes in the scale of C are minor, except chord VII - the notes B – D – F, which is diminished. When a seventh is added to a chord this is known as a seventh chord.
These were usually major or minor chords. The score below is from Sicut Cervus by Giovanni Pierlugi da Palestrina. The notes on the first and third beats of the bar form part of a chord in G major ...