Hydridits

Hydridits are a proposed class of mineral compounds distinguished by the incorporation of hydride ions (H−) within their crystal structures. The term hydridit combines the concept of hydrogen in a hydride state with the standard mineral naming convention, -ite. In current mineralogical discussions, hydridits are described as hydrogen-rich, metal-bearing minerals that may form under highly reducing, hydrogen-active conditions.

Composition and structure

Hydridits are envisioned as frameworks in which hydride ions occupy interstitial sites or form hydride bonds with metal cations. The presence of H− is expected to influence charge balance, lattice parameters, and bonding characteristics, potentially producing distinctive vibrational or electronic signatures. In proposed models, hydridites could crystallize in a range of symmetries, with structures that accommodate hydrogen ordering at low temperatures.

Formation and occurrence

The hypothesized environments for hydridite formation include hydrogen-rich fluids interacting with metal-bearing rocks under reducing conditions, and high-pressure, high-temperature settings such as deep crustal or mantle analogs. Some studies explore synthetic routes to hydridites to understand their stability fields and potential parallels with known hydride materials.

Properties and identification

Theoretical hydridites are predicted to exhibit moderate to high hardness and notable thermal stability in hydrogen-rich environments. They may show characteristic infrared or Raman features associated with hydride vibrations, aiding spectroscopic identification. Density and elastic properties would depend on the specific metal-hydride framework.

Status

As of now, no universally accepted natural hydridite specimen has been reported, and hydridites remain primarily a topic of theoretical, experimental, and modeling interest. Ongoing research seeks to confirm their existence and explore potential natural occurrences.