sedimentary

Banded Iron Formation

Banded Iron Formation (BIF)

AI-generated identification · may be incorrect

Hardness of 5-6 on the Mohs scale with distinctive alternating red, brown, black, and gray bands. Luster ranges from metallic to dull, and specific gravity is around 3.2-4.5.

Identified October 18, 2026More sedimentary →

Explore Banded Iron Formation in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness of 5-6 on the Mohs scale with distinctive alternating red, brown, black, and gray bands. Luster ranges from metallic to dull, and specific gravity is around 3.2-4.5.

Formation & geological history

Formed in marine environments during the Precambrian era, around 1.8 to 3.8 billion years ago, through the chemical precipitation of iron oxides and silica.

Uses & applications

Primarily mined as the world's most important ore for iron and steel production, with lower-grade banded chert occasionally used for decorative lapidary items.

Geological facts

BIFs are direct evidence of Earth's Great Oxidation Event, representing the moment photosynthetic organisms began producing free oxygen in the oceans.

Field identification & locations

Easily identified in the field by its striking striped appearance featuring dark iron-rich bands alternating with lighter chert layers. Found globally in ancient cratons.