ironstone

Black-band ironstone, 2.1 billion years old.

Close-up of Banded Iron Formation specimen from Upper Michigan. Scale bar is 5.0 mm.

Ironstone is a fine-grained, heavy and compact sedimentary rock. Its main components are the carbonate or oxide of iron, clay and/or sand. It can be thought of as a concretionary form of siderite. Ironstone also contains clay, and sometimes calcite and quartz.

Appearance

Freshly cleaved ironstone is usually grey. The brown external appearance is due to oxidation of its surface. Ironstone, being a sedimentary rock is not always homogeneous, and can be found in a red and black banded form called tiger iron, sometimes used for jewelry purposes.

Sometimes ironstone hosts concretions or opal gems.

Occurrence

Ironstone mostly occurs in the form of nodules, for example in seams in the coal measures.

Uses

Ironstone as a source of iron

Ironstone is a bountiful and widespread source of iron (Fe), although it only contains less than 50 percent iron, far less than the other main source of iron, hematite. Historically, most of British iron originated from ironstone, but it is now rarely used for this purpose.

Ceramics

Ironstone is used as a component in some ceramics, commonly known as "ironstone china". Josiah Wedgwood also manufactured a "stoneware" china in the 19th century. It was commonly used for heavy-duty dinner services in the 19th century.^[1] Charles James Mason (son of the potter Miles Mason) took out a patent for "Mason's Ironstone China" in 1813.^{[citation needed]} Ironstone china was very popular during the 1970s.

In construction

The stone can also be used as a building material. Examples include the parish church at Kirby Bellars in Leicestershire.

See also

Wikimedia Commons has media related to: Ironstone

• Iron ore
• Banded iron formation

References

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