Amastra petricola is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Amastridae.

Its coloration is a rich, dark, horn-like tone, accentuated by the outer and columellar lips, which are delicately edged with white or pale yellowish-white.

The embryonic shell is finely marked with extremely delicate longitudinal striae, while the later whorls display coarse, low growth folds.

Fresh specimens exhibit a very thin, dull light-brown cuticle over a glossy underlying layer that can appear in angular patches.

The columella is vertical, its edge reflexed into a narrow triangular shape that overhangs the umbilicus and forms a slight channel at its junction with the basal lip.