Iron oxide color

Iron oxides are a type of chemical compounds composed of iron and oxygen. In total, sixteen known iron oxides and oxyhydroxides are present. There lies a great variety of usage for these various oxides and hydroxides ranging from pigments in ceramic glaze, to use in thermite.

Hematite is a key ore of iron and its blood red color (in the powdered form) provides itself well to use as a pigment. The name Hematite is derived from a Greek word meaning blood-like because of the color of its powder. There exists ancient superstition which tells that big deposits of hematite were formed from battle fought in ancient times by the blood that flowed into the ground. Crystals of Hematite are thought to be rare and are desired by collectors as are fine Kidney Ore specimens.

Properties of iron oxide

The color ranges from steel or silver gray to black in some forms and red to brown in earthy forms. Occasionally it is tarnished with gleaming colors when in a hydrated form (called Turgite).The luster is metallic or dull in earthy and oolitic forms. Transparency: Crystals are opaque. Crystal System is trigonal; bar 3 2/m Crystal Habits include tabular crystals of varying thickness sometimes twinned, micaceous (specular), botryoidal and massive. also earthy or oolitic. Cleavage is absent.

However, there is a parting on two planes.

Fracture is uneven. Hardness is 5 – 6. Specific Gravity is 5.3 (slightly above average for metallic minerals). Streak is blood red to brownish red for earthy forms. Associated Minerals include jasper (a variety of quartz) in banded iron formations (BIF or Tiger Iron), dipyramidal quartz, rutile, and pyrite among others.

Forms of iron oxide

Iron Oxide is present in many different forms which are mentioned below:

a. Alpha phase- In the Alpha phase, most common form is Rhombohedric, and occurs as the mineral hematite.

b. Beta Phase- The Beta phase is cubic face centered or metastable.

c. Gamma Phase- The Gamma phase is cubic, metastable.

d. Epsilon phase- The Epsilon phase is rhombic and has properties in between the alpha and the gamma phases.