[9][10] The mineral occurs as thin films, aggregates of fine fibers, botryoidal masses, and interstitial filling in host sandstone.

[4] In Argentina, the mineral formed after mine tunnels were cut through Cu-U deposits in sandstone and conglomerate.

The solution is then concentrated, excess vanadic acid is removed by filtration, and allowed to cool and crystallize.

[13] The crystal structure consists of decavanadate anions (V10O28)6− linked by an interstitial complex of isolated [Mg(H2O)6]2+ and an infinite zigzag chain of [Na4(H2O)14]4+.

[10] The first specimen was collected in 1959 by V. Angelelli of the Geology Department of CNEA on level -18 of the Agua Botada ore body.

In 1964, the unit cell was measured at Yale University by Linares and H. Winchell and the mineral's chemical and physical properties were checked by C. E. Gordillo and R. O.

[13] Huemulite in its natural form is too fine-grained for accurate study of its physical and optical properties;[17] however, it can readily be recrystallized after dissolving the mineral in water.