 Ca3P2 is a new high-temperature form of this compound, which has a crystal structure of the hexagonal Mn5C3 type. It contains a Caion deficiency compared to the ideal 5-colon-3 stoichiometry, resulting in a stable, charge-balanced compound of Ca2+, and P3. Additionally, we observed a secondary hydride phase, Ca5P3H, which is a charge-balanced compound. Ca3P2 is a three-dimensional Dirac semi-metal with a highly unusual ring of Dirac nodes at the Fermi level, which is protected by a mirror plane similar to graphene. This article was authored by Lilia Essier, Leslie M. Scope, Elizabeth M. Seibel, and others.