Abstract: Olivines containing up to 6.1 wt.% P₂O₅ occur in association with apatite and an unnamed NaCaMg phosphate phase. Phosphoran olivine has been recorded only in pallasite meteorites and from one other terrestrial occurrence. The rarity of palpable phosphorus substitution for silicon may be related to the fact that in most terrestrial rocks, phosphorus is incorporated initially, and remains as, apatite; thus phosphorus excess in an undersilicated environment must be uncommon. However the highly capricious distribution of phosphorus in individual olivines from this and the meteoritic occurences suggests disequilibrium, and questions whether phosphoran olivine is ever stable relative to combinations of P-free olivine and phosphate/phosphide minerals.