Chemically deposited cherty sedimentary rock, usually thinly bedded and containing more than 15% iron.
BIF; alternating layers of iron-rich and iron-poor rocks. Most rocks of this type are older than about 2 billion years old and indicate the presence of oxygen.
rock consisting of alternating light and dark layers of iron-rich chert (the dark layers have more iron minerals) formed from 3.8 to 1.7 Billion years Ago Breccia a rock comprising mixed particles or fragments which are angular in shape and make up an appreciable volume of the rock.
A bedded deposit of iron minerals.
A chemical sedimentary rock containing at least 15% iron of sedimentary origin, showing marked banding of iron-rich minerals and chert or quartz
Banded iron formations (also known as banded ironstone formations, or BIFs) are a distinctive type of rock often found in old sedimentary rocks. The structures consist of repeated thin layers of iron oxides, either magnetite or hematite, alternating with bands of iron-poor shale and chert. Some of the oldest known rock formations, formed around three thousand million years before present (3 Ga), include banded iron layers, and the banded layers are a common feature in sediments for much of the Earth's early history.