By a few devotional ejaculations--"Heaven's Mother send us grace!" "To Mary Queen the praise be given!"-- we are made to feel that the Ancient Mariner lived before the Reformation, in the ages of wonder and faith.

Repetition, as in many stanzas of Part IV., is a device caught from the folk-ballad and modified to produce the effect of a spell, which is so strong a mark of the poem.

The abrupt opening, the unannounced transitions in dialogue, the omission of all but the vital incidents of the story, all belong to the ballad style.

The verse form is what is known as the ballad stanza (stanza of four lines--a line of four accents followed by one of three, the second and fourth lines riming) variously extended and modified to suit the mood of the passage.

The prose summary in the form of a marginal gloss, first added in the edition of 1817, is a practice taken from early printed books, but not from balladry, which is normally oral.
Of the literary qualities of the poem much might be said, but I call attention here to but two: the organic structure of the story and the character of the imagery, two important aspects of creative imagination.
The seven parts are seven stages of the narrative, each, except the last, closing with a reference to the Mariner's sin.