Ilmenites from alkaline basic dykes in the Gardar province, south Greenland have Zr contents up to 3850ppm and Nb contents up to 1030ppm. These elements substitute for Ti in the octahedral site. These are amongst the highest recorded Zr and Nb contents for ilmenites, giving distribution coefficients (Kdilmenite/matrix) for Zr up to 11.6 and Nb up to 70.3. Fractionation of ilmenite may thus have a dramatic effect on residual Zr and Nb contents. These effects are discussed in relation to the use of trace element tectonomagmatic discrimination diagrams.

Sodic-calcic and alkali amphiboles from benmoreitic members of the Igaliko Dyke Swarm contain up to 4.13 wt. % ZrO2. It is proposed that Zr enters the amphiboles by a coupled substitution of

(where C = octahedral site and T = tetrahedral site) to produce the richest Zr-bearing amphiboles so far identified, with compositions ranging up to

These amphiboles crystallize at a late stage from magmas which were Zr-rich, highly peralkaline and hydrous, with an fo2 close to the synthetic QMF buffer. The incorporation of Zr in to the amphibole is a consequence of the failure of other Zr-bearing phases (such as zircon, baddeleyite, eudialyte) to crystallize.