New Arsenate Mineral Belmonteite Discovered in Eastern Liguria

A team led by Cristian Biagioni has announced the discovery of Belmonteite, a previously unknown arsenate mineral located in the manganese ore deposits of Graveglia Valley, eastern Liguria, Italy.¹

The mineral’s chemical formula is CaMn₂(AsO₄)₂(H₂O)₅·2H₂O. Its crystal structure features {010} layers composed of six‑fold coordinated Mn atoms that are decorated on both sides by (AsO₄) groups and calcium atoms linked through hydrogen bonds. These structural characteristics were revealed using X‑ray diffraction, electron microscopy, and spectroscopic analyses.¹

Belmonteite formed during late metamorphic events when As‑rich oxidizing fluids circulated within the host manganese ores. The name honors Donato Belmonte for his long‑standing contributions to Ligurian mineralogy.

The identification of this new species adds another member to the family of arsenates known to form under low‑temperature, oxidizing conditions and provides fresh structural data on layered Mn–Ca–As systems.