Magnetite skarn - Haytor
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Fact sheet
Description: 

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.

In Place
In Time
Accuracy:
Location precision: 
Moderate
Timescale:
Timescale: 
Carboniferous
Ma = Millions of years ago
In Focus
Type:
Type: 
metamorphic
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Rock-forming minerals:

Rock forming mineral:

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