Magnetite skarn - Haytor
Collection:
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Fact sheet

Magnetite skarn - Haytor

Haytor Iron Mine [SX 773 772] is situated within the metamorphic aureole of the Dartmoor Granite, with the contact lying some 500m to the east. The ores are hosted conformably in metapelite probably of Lower Carboniferous age. The ore consists of finely intergrown magnetite and green-brown amphibole (ferro-edenite) which may be massive, or show banding marked by varying proportions of the two minerals. Coarse crystals of magnetite are present on some joint surfaces and the amphibole forms coarse fibro-radiate aggregates in places.

The deposit also hosts coarse garnet (andradite), axinite, siderite, calcite and apatite. Additionally, pseudomorphs of chalcedony after datolite, originally termed 'Haytorite', have been recorded. Traces of sulphides are present in the ore beds and include arsenopyrite, pyrite, sphalerite and chalcopyrite (tarnished crystals of chalcopyrite mantled by magnetite are visible in the thin section).

The paragenesis of this deposit is typical of infiltration exoskarns elsewhere in the region, with an early thermal metamorphic phase of silicate growth succeeded by the development of ore minerals from high temperature hydrothermal fluids.

Many thanks to Richard Scrivener for providing this sample.

Map
50.586971, -3.736553
Precision:
Moderate
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

Type
metamorphic
Rock forming mineral
amphibole
ferro-edenite
magnetite
Category guide  
Category Guide
Title
Refers to any word or phrase that appears in the individual rock names. Names are generally descriptive; they allow the user to searranite' as well as more speci?c names such as 'breccia'. However, the adjacent descriptiix captures a wider range of general words and phrases and is a more powerful search tool.
Description
Refers to any word or phrase that appears anywhere in the descriptions of the specimens
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.
Timescale
Selecting one or more period, for example 'Jurassic'.
Theme
A term used to group togge.g. the UKVM contains a 'SW England granites' theme that includes such rock types as granite, hydrothermal breccia, skarn, and vein samples).
Category
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).
Owner
The owner of the sample that appears in the collection. For example, NASA owns all the samples that appear in the Moon Rocks collection
We would like to thank the following for the use of this sample: