What is the name of the palantír kept in Minas Tirith?

The palantír kept in Minas Tirith is called the Anor-stone. It is one of the seeing-stones brought to Middle-earth by Elendil and his sons after the downfall of Númenor.

The Anor-stone was housed in the White Tower of Minas Tirith and remained in the keeping of Gondor's ruling Stewards. During the War of the Ring, Denethor used it to look across Middle-earth. The stone showed him the immense forces gathering against Gondor, but Sauron's influence and selective presentation caused Denethor to draw a despairing conclusion from what he saw.

Palantíri were powerful crystal spheres used to observe distant places and communicate with users of other stones. They could reveal true images, but they did not guarantee a complete or unbiased understanding. That limitation is central to Denethor's tragedy: the visions were not simply false, yet they concealed the possibility of rescue.

The name “Anor-stone” refers to Minas Anor, the earlier name of Minas Tirith. It is not the same stone as the Orthanc-stone, used by Saruman and later Pippin, or the Ithil-stone, originally kept in Minas Ithil and eventually controlled by Sauron.