Pyrite sandstone pitcher stamped "Roman", 70s

Pitcher in pyrite sandstone from the 70s. Stamped "roman". Excellent condition outside. Inside there are rough edges that resist my vigorous cleaning! I do not know if it is a form of tartar or if it is simply a manufacturing defect. Because of these rough edges I recommend a decorative use for this object. Height 15 cm. Width at base 10.5 cm.