The 21-year-old, who was visiting the famous archaeological site with her father and sister, had crossed a protective railing and was seen using a tool to dislodge the mosaic tiles – called tesserae – from the floor mosaic in the House of the Anchor.
Staff called local caribinieri police, who detained the woman as she tried to leave the area.
The incident caused some €3,000 worth of damage, the site’s manager estimated.
Pompeii has long struggled with unscrupulous visitors who pocket relics as holiday souvenirs, or even to sell for a profit.
Last year a French tourist was fined and given a suspended prison sentence after he tried to leave Pompeii with a backpack stuffed full of ancient artefacts.
Sometimes however, the thieves try to make amends. In 2014, a Canadian tourist returned an artefact she had stolen from Pompeii's amphitheatre during her honeymoon – 50 years earlier.
And several thieves have sent back their loot claiming the relics are 'cursed'.
An exhibition of the returned artefacts and accompanying letters of apology has recently been set up at the site in the hopes of deterring would-be thieves.