This image shows a 2.1 billion years old rock containing black-banded ironstone, which has a weight of about 8.5 tons. The approximately two meter high, three meter wide, and one meter thick block of stone was found in North America and belongs to the National Museum of Mineralogy and Geology in Dresden, Germany.
Ironstone is a heavy, compact rock containing iron minerals. Typically ironstone is fine-grained and consists of clay and various iron minerals. Also it may contain other minerals such as calcite and quartz. In Ohio, most ironstone occurs in the eastern part of the state.
Although it is not as rich in iron as other substances, ironstone often is used as an ore for commercial production of iron. The mineral hematite is about 70% iron and makes the best ore for that metal. In contrast, less than half of ironstone is iron. Even so, much of the iron produced by Great Britain is made from ironstone.
- Coogan, Allan H. Ohio’s Surface Rocks and Sediments; Chapter 3 in Fossils of Ohio, edited by Rodney M. Feldmann; Ohio Geological Survey, Bulletin 70, 1996.
- Pough, Frederick H. A Field Guide to Rocks and Minerals; Houghton Mifflin, Boston, MA; 1976.
- Sorrell, Charles A. Rocks and Minerals; Golden Press, New York, NY; 1973