Area: 0.8 hectares.
In County Structure Plan Area of Great Landscape Value
This site is the world type locality of the aluminium phosphate mineral wavellite. The quarry faces expose black carbonaceous cherty slates of the Coddon Hill Beds with wavellite crystals sparingly present along cleavage joints. In an overgrown part of the quarry numerous pits made by mineral collectors have covered the floor with a scree-like debris in which many good examples of typically radiating wavellite crystals can be seen on joint surfaces. The only British record of the rare variscite (also an aluminium phosphate) is from High Down. The variscite is intimately associated with wavellite. Present day samples are just as good as those figured in Sowerby’s British Mineralogy of 1806 and this is a rare example of classific mineral type locality which is still productive. The genesis of the wavellite has not been discussed.
Simplified Statement of Interest:
(This statement should not be taken as definitive and further information as to details of the interest can be obtained from the Nature Conservancy Council.)
High Down Quarry is of special geological importance for two reasons. Firstly, it is the locality from which the mineral wavellite was first described and is recognised internationally as the ‘type-locality’ for that mineral. Secondly, it is the only known locality in Britain where the rare mineral variscite can be found. Good examples of both minerals can still be collected from High Down Quarry, which is most unusual in a locality first described more that 175 years ago.