The Mars meteorites were found May 25 and NASA released a detailed photo of the Lebanon meteorites on Tuesday.
Curiosity took detailed pictures of the main Lebanon meteorite using its high-resolution Chem-Cam and Remote Micro-Imager cameras. The images revealed strange angular cavities in the surface of the rock.
"That 'Lebanon' is huge, almost 7 feet," NASA spokesman Guy Webster from the agency's Jet Propulsion Laboratory in California was quoted by Space.com as saying.
Webster said Curiosity also found a third meteorite at the same time it spotted the Lebanon rocks.
In a raw photo from Curiosity, the third meteorite - which is also about 7 feet wide - can be seen just beyond the closer Lebanon meteorites.
"Heavy Metal! I found an iron meteorite on Mars," Curiosity's handlers wrote on the mission's Twitter page.
The three meteorites are the first space rocks on Mars discovered by the Curiosity rover since it landed on the Red Planet in August 2012, Webster added.
"One possible explanation is that they resulted from preferential erosion along crystalline boundaries within the metal of the rock," NASA officials wrote in a statement.
"Another possibility is that these cavities once contained olivine crystals, which can be found in a rare type of stony-iron meteorites called pallasites, thought to have been formed near the core-mantle boundary within an asteroid."