Oolitic Ironstone – Stanion Lane Railway
Click the microscope button to view a thin section for this sample.
Click the microscope button to view a thin section for this sample.

Fact sheet

Oolitic Ironstone – Stanion Lane Railway

Northampton Sand Ironstone is a sedimentary rock unit of Jurassic age that extends from Lincoln to Towcester in Northamptonshire, and this sample is from Stanion Lane railway, near Corby. This rock was a major source of iron ore for the steel manufacturing towns of Corby and Kettering. The ironstone has been secondarily enriched by weathering which caused dissolution of calcium and iron carbonate, and oxidation of the iron minerals to limonite, increasing the iron content of the rock.

In thin section this oolitic ironstone is composed of spherical concretions (ooids), cemented by fine grained sparry calcite. Note that several of the ooliths were lost during the preparation of the thin section. The ooliths formed in shallow, well-stirred water in which chemical precipitation of iron compounds predominated. Ooliths consist of concentric growths around a nucleus, which may be a shell fragment, quartz grainor algal pellet. The mineral chamosite is the most common constituent of the ooliths. Siderite and limonite are secondary iron-rich species that replace chamosite, and also authigenic magnetite and pyrite, contributing to the elevated iron content of the rock.

Additional images
52.4749, -0.6425
Stanion railway line near Corby, Northamptonshire
About this collection

The United Kingdom Virtual Microscope (UKVM) collection consists of igneous, sedimentary and metamorphic rocks from around the UK.

It is intended as a teaching resource, helping to tell the story of the common rock types and how they form, and reflecting the history of the UK at the margins of the continent of Europe. The collection is a series of teaching sets, for example igneous rocks from the North Atlantic Igneous Province and SW England; high-temperature metamorphic rocks from Scotland and low-temperature metamorphic rocks from Wales; and sedimentary rocks, including English limestones and sandstones.

Sample details

Rock-forming mineral
Category guide  
Category Guide
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Accessory minerals
Minerals that occur in very low abundance in a rock. They are usually not visible with the naked eye and contribute perhapssver, they often dominate the rare elements such as platinum group metals.
Rock-forming minerals
Minerals that make up the bulk of all rock samples and are also the ones used in rock classi?cation.
Selecting one or more period, for example 'Jurassic'.
A term used to group together related samples that are not already gathered into a single Collection. For instance, there is a ‘SW England granites’ theme that includes such rock types as granite, hydrothermal breccia, skarn and vein samples.
A general term used to label a rock sample. It is a useful way of grouping similar samples throughout a collection. Category names are often, but not exclusively, common rock names (e.g. granite, basalt, dolerite, gabbro, greisen, skarn, gneiss, amphibolite, limestone, sandstone).
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We would like to thank the following for the use of this sample: