Among them were enlargement of the false tower at the top, more modern engines, installation of a radiogoniometer that could be controlled from inside the ship.

[1] Malachite was built by OTO at their shipyard in Muggiano, laid on 31 August 1935, launched on 15 July 1936 and completed on 6 November 1936.

Upon her return to Italy, she was assigned to 47th Squadron (IV Submarine Group) based at Taranto.

At the time of Italy's entrance into World War II, Malachite was reassigned to the X Submarine Group based at Augusta.

On February 14 she attempted an attack on an unidentified warship, but fails to launch torpedoes due to the high speed of the target.

At 23:37 on April 14 Malachite sighted a large convoy but was prevented from attacking it due to preemptive action by the escorts.

[5][8] On the night of June 19, 1941 while patrolling off Crete, Malachite sighted a British cruiser escorted by a destroyer.

At 20:00 on July 3 Malachite sighted a large cruiser (possibly HMS Phoebe) escorted by two destroyers, and immediately launched a torpedo.

[5] On July 16, 1942 Malachite was sent to patrol along the Tunisian coast, however had to return to the base the next day due to engine failure.

[5] From 16 to 24 December 1942 she patrolled an area between the island of La Galite and Cape de Fer.

[5][4] On February 2, 1943 Malachite left Cagliari with a group of 11 commandos from the battalion "San Marco" whose goal was to blow up a railway bridge in El Kejur, Algeria.

[5][10][4] In the evening of February 6, the commandos landed by Cape Matifu, while the submarine remained on station waiting for their return.

[5][10] An explosion was heard some time later, and a signal rocket was launched indicating success of the operation.

[5][10] Malachite was heading to her base in Cagliari, when already in view of the Sardinian coast she was spotted by the Dutch submarine HNLMS Dolfijn in the morning of February 9, 1943.

[11] The Italian submarine managed to avoid three of them by deftly maneuvering, but the fourth one hit her on the stern, and she sank within a minute, taking down 35 crew with her.