Physical and Chemical Indexes
Color: black-gray
Appearance: loose pigment
Density: 2.79 — 2.82 g/cm3
Hardness: 5.0-5.5 (Mohs' scale)
Mesh: -325 （Φ43.5μm）or -200 （Φ80μm）
Chemical content: Fe ≥71%, Fe3O2.+FeO ≥94%, other≤0.5%
Corrosion resistance: in 5% NaCl solution for 24 hours, no rust stain noted.
Micro-structure
Photographed at a magnification of 2000 times by an electron microscope.
Photographed at a magnification of 4300 times by an electron microscope.
Photographed at a magnification of 10000 times by an electron microscope.
