Search results
Results from the WOW.Com Content Network
Iron formations must be at least 15% iron in composition, just like ironstones and all iron-rich sedimentary rocks. However, iron formations are mainly Precambrian in age which means that they are 4600 to 590 million years old.
Banded iron formation – Layered iron-rich sedimentary rock Breccia – Rock composed of angular fragments Calcarenite – Type of limestone that is composed predominantly of sand-size grains
Ironstone (sandstone with iron oxides) from the Mississippian Breathitt Formation, Mile Marker 166, I-64, Kentucky. Ironstone is a sedimentary rock, either deposited directly as a ferruginous sediment or created by chemical replacement, that contains a substantial proportion of an iron ore compound from which iron (Fe) can be smelted commercially.
Iron-rich sedimentary rocks are composed of >15% iron; the most common forms are banded iron formations and ironstones. [ 6 ] Phosphatic sedimentary rocks are composed of phosphate minerals and contain more than 6.5% phosphorus ; examples include deposits of phosphate nodules , bone beds, and phosphatic mudrocks.
Iron oxides are derived from mafic igneous rocks and other iron-rich rocks; bauxites are derived from granitic igneous rock and other iron-poor rocks. [15] Nickel laterites occur in zones of the earth which experienced prolonged tropical weathering of ultramafic rocks containing the ferro-magnesian minerals olivine, pyroxene, and amphibole. [10]: 3
2.1 billion year old rock from North America showing banded iron formation, displayed in Dresden, Saxony, Germany. Banded iron formations (BIFs; also called banded ironstone formations) are distinctive units of sedimentary rock consisting of alternating layers of iron oxides and iron-poor chert. They can be up to several hundred meters in ...
Following development of high grade direct shipping iron ore deposits on the Mesabi Range, containing up to 65% iron and as little as 1.25% silica, miners termed the unaltered iron-formation wall rock taconite. The iron content of taconite is generally 30% to 35%, and the silica content generally around 45%.
Pages in category "Iron ores" The following 14 pages are in this category, out of 14 total. ... Iron-rich sedimentary rocks; Ironsand; Ironstone; L. Limonite; M ...