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At the type locality, jeremejevite occurs as a hydrothermal mineral in granitic pegmatites, as in most other deposits, except for Germany where the crystals are hosted in alkali lavas. A gem-quality jeremejevite crystal partly embedded in feldspar, 2.6 cm, Mile 72, Namibia. Rarity and beauty are perhaps two of the most important attributes when defining minerals desired by the connoisseur, and jeremejevite certainly fulfils both these criteria. The jeremejevite often occurs as tiny blue to pale yellow crystals or clusters of crystals, typically on highly vitreous sanidine (Blass and Graf [3]). [Extracted from the article]

In one type, the cavity walls are coated by descloizite crystals and other supergene minerals; in the other, the walls are devoid of crystals, but the cavities are partially or wholly filled with loose vanadiferous sand and mud. Small, spear-shaped dipyramidal descloizite crystals first formed over the dolomite; these were then overgrown by semirounded descloizite crystals. One form of descloizite that was more prevalent at the Abenab mine is descloizite pseudomorphs after vanadinite, ranging from thin descloizite coatings around stout vanadinite crystals to 12 cm in length, to complete replacement by descloizite producing hollow pseudomorphs after vanadinite. Drusy quartz is most commonly associated with descloizite and, together with calcite, dolomite, goethite, and willemite, can form the matrix of some descloizite crystals. "[Berg Aukas is] without question the world's best locality for crystallized specimens of descloizite" (Moore [38], p. 473). [Extracted from the article]