Close House Mine is a Site of Special Scientific Interest

Site of Special Scientific Interest

A Site of Special Scientific Interest is a conservation designation denoting a protected area in the United Kingdom. SSSIs are the basic building block of site-based nature conservation legislation and most other legal nature/geological conservation designations in Great Britain are based upon...

 in the Teesdale

Teesdale (district)

Teesdale was, from 1974 to 2009, a local government district in County Durham, England. Its council was based in Barnard Castle and it was named after the valley of the River Tees....

 district of west County Durham

County Durham

County Durham is a ceremonial county and unitary district in north east England. The county town is Durham. The largest settlement in the ceremonial county is the town of Darlington...

, England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

. It is a working opencast mine located in Arngill Beck on the north-east flank of Close House Crags, in the Lunedale Forest. The site is surrounded on three sides by the Upper Teesdale

Upper Teesdale

Upper Teesdale is a Site of Special Scientific Interest in the Teesdale district of west County Durham, England. It encompasses an extensive upland area that includes the headwaters of the River Tees and the surrounding catchment area upstream of the village of Langdon Beck.The site has a diverse...

 SSSI.

The mine is situated within the Lunedale

Lunedale

Lunedale is a dale, or valley, of the east side of the Pennines in England, east of Middleton-in-Teesdale. Its principal villages are Grassholme, Thringarth and West Pasture. Lunedale is part of County Durham....

 fault system, at the southern limit of the Alston Block

Alston Block

The Alston Block is a term used by geologists to describe the geological structure of the North Pennines of northern England and which forms a part of the Pennine Block & Basin Province which originated during the Carboniferous period. It is defined by the Stublick and Ninety Fathom Faults to the...

. A large barite

Barite

Baryte, or barite, is a mineral consisting of barium sulfate. The baryte group consists of baryte, celestine, anglesite and anhydrite. Baryte itself is generally white or colorless, and is the main source of barium...

 ore body

Mining

Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

 is exposed at the mine and a rare mineral, rosasite

Rosasite

Rosasite is a carbonate mineral with minor potential for use as a zinc and copper ore. Chemically, it is a copper zinc carbonate hydroxide with a copper to zinc ratio of 3:2, occurring in the secondary oxidation zone of copper-zinc deposits. It was originally discovered in 1908 in the Rosas mine in...

, has been identified at the site.