Ferrous chlorborate, FeCl₂.6FeO.8B₂O₃

Ferrous chlorborate, FeCl₂.6FeO.8B₂O₃ or FeCl₂.6FeB₂O₄.2B₂O₃, is obtained by passing the vapour of ferric chloride over an intimate mixture of iron wire and calcium borate heated to 380° C. The ferric chloride is reduced to ferrous, which immediately reacts with the calcium borate. The mass, on cooling, is extracted with water, any unattacked iron being removed magnetically. Ferrous chlorborate yields greyish, transparent cubes. It is slowly attacked by nitric acid; fused alkalies rapidly decompose it.