The formation of phosphoran olivine by crystallization from a melt was investigated experimentally using a one atmosphere furnace, using San Carlos olivine [(Mg,Fe) 2 SiO 4 ] mixed with either iron phosphide (FeP) or magnesium pyrophosphate (Mg 2 P 2 O 7 ). Both dynamic crystallization and isothermal experiments produced phosphoran olivine as zoned single crystals and as overgrowths surrounding normal, phosphorus-free olivine grains. The crystallization pathways that form phosphoran olivine were traced and confirm that it is a metastable phase that can crystallize from a phosphorus-rich melt over timescales of hours to days. Removal of the P and equilibration of the olivine however requires weeks to months in the presence of silicate melt. Phosphoran olivine with up to 27 wt% P 2 O 5 was generated and up to 69% of the Si tetrahedral sites were replaced by P. The substitution of Si by P into olivine was confirmed as 4 VI M +2 + 2 IV Si +4 ↔3 VI M +2 + 2 IV P +5 + VI []. Phosphoran olivine compositions that vary from (Mg,Fe) 2 SiO 4 to (Mg,Fe) 1.65 [] 0.35 Si 0.3 P 0.7 O 4 have been produced in these experiments.Phosphoran pyroxene was also generated in a few experiments and forms when phosphoran olivine reacts with either tridymite or melt. It has compositions compatible with protopyroxene, orthopyroxene, pigeonite and sub-calcic augite, and can contain up to 31.5 wt% P 2 O 5 . Like phosphoran olivine, it is also a metastable phase. Phosphorus replaces Si in pyroxene by the following substitution methods: 8 IV Si +4 ↔3 IV Si +4 + 4 IV P +5 + IV [] with Al entering the structure by the exchange 2 IV Si +4 ↔ IV Al +3 + IV P +5 . Phosphoran pyroxene compositions vary from (Mg,Fe) 8 Si 8 O 24 to (Mg,Fe) 8 Si 3 P 4 []O 24 .