leucopyrite

The story

1. Proto-Indo-European*lewk-
2. Proto-Indo-European*lewkós
3. Proto-Hellenic*leukós
4. Ancient Greekλευκός (leukós)
5. Englishleuco-
6. Proto-Indo-European*péh₂wr̥
7. Proto-Hellenic*pāwər
8. Ancient Greekπῦρ (pûr)
9. Ancient Greekπῠρῑ́της (pŭrī́tēs)
10. Latinpȳritēs
11. Old Frenchpyrite
12. Englishpyrite
13. English todayleucopyrite

From leuco- + pyrite.