Banded Iron Display Mineral 644 grams or 1.4 lbs of Magnetite, Hematite & Jasper Approximately 2.5 x 3.5 x 2.25 inches Origin: Wyoming Banded Iron is a from of sedimentary rock ranging from 1.8 to 2.5 billion years old. A typical Banded Iron formations consists of repeated, thin layers of iron oxides - either Magnetite (Fe3O4) or Hematite (Fe2O3) - alternating with bands of iron-poor shale and chert. This piece is "naturally polished" by rain/wind/water erosion