Čechite, a rare vanadate from the Ulldemolins mines (Catalonia)

Čechite is a very rare lead and iron hydroxylvanadate, with the formula PbFe²⁺(VO₄)(OH), which has been found in very few localities worldwide. The first world location in which it was determined was in the Vrančice mines, in the Czech Republic, in the early 1980s. It has subsequently been found in Italy and the United States. It has no industrial interest, despite the fact that vanadium is a strategic element, since this mineral occurs in small quantities. 

This species usually appears as small tabular to equidimensional crystals, with a black color and a resinous to submetallic luster. The best crystals known until recently were those of the Czech Republic.

In the mid-2010s, conducting studies at the “María Magdalena” mine in Ulldemolins (Priorat, Tarragona, Catalunya), we found some mineral species that contained vanadium, such as vanadinite, descloizite or mottramite.

But in a very specific area of mining works, small black crystals appeared that made us think on hematite, an iron oxide. We didn't give them more importance until we decided to analyze them, a task we do routinely when studying a deposit. Our surprise was remarkable when the analyzes yielded results indicating that it was an iron-lead vanadate. Later studies of the crystals showed that they were the rare čechite. If the fact that this species was determined for the first time in Catalonia is already interesting in itself, the most remarkable thing is that Ulldemolins crystals are considered to be the best čechite known worldwide.

All this work was published in the magazine “Mineralogistes de Catalunya” (in Catalan) and in “Paragénesis” (version in Spanish of MdC), both edited by the Grup Mineralògic Català.

BIBLIOGRAPHY

Rosell J, Rubio C, Varela F (2017): Los minerales de vanadio de la mina "María Magdalena", Ulldemolins, el Priorat, Tarragona. Paragénesis 2017, issue 1, 3, 44-48. [online]