The Heights mine, situated between the villages of Eastgate and Westgate, is comprised of numerous underground workings established on three primary veins: Heights North, Heights South, and West Cross. These veins are roughly parallel, with the West Cross vein intersecting them. The main objective of these workings was to access the associated flats at the High Flats horizon within the Great Limestone.

Although lead extraction from the flats was attempted by the Beaumont Company in the early 1860s, the principal focus of mining at Heights was iron ore. The Weardale Iron Company operated the mine between 1850 and 1868, exploiting commercial iron deposits found in the flats adjacent to the veins. These deposits consisted of limonite resulting from the oxidation of iron carbonates such as ankerite and siderite.

The flats surrounding the main veins are notably vuggy and have yielded impressive specimens of twinned emerald-green fluorite, with crystals reaching sizes of up to 4 centimeters. Additionally, well-formed specimens of pale purple to colorless fluorite have been discovered, often accompanied by galena, calcite, and aragonite. Some larger, opaque green fluorite crystals measuring up to 8 centimeters have also been encountered.

The old underground workings, once a source of specimens for amateur collectors, became hazardous and were sealed off in the late 1970s. However, recent quarry operations in the area have led to the exposure of portions of the South and West Cross veins. As a result, occasional specimen recovery has resumed in these areas, offering opportunities for collectors to obtain fluorite and other minerals.

1950 Anglo Austral Mines Ltd