Fluorite, a 2.5-cm penetration twin on a 5.5-cm ironstone matrix, from the Heights mine, Weardale, Durham (LG-18). Collected in July 1977 by Richard Barstow. Ex Barstow collection; Jesse Fisher photo. mine, and collectors once again had access to this famous fluorite locality. Opaque, deep green cubic fluorite crystals to 12 cm were collected from mud-filled cavities on the West Cross vein, and more fine specimens were dug near the South vein: good milky purple to gray, blue-green and “classic” bottle-green fluorite crystals emerged and were marketed during the 1990s. However, as of the mid-2000s, illicit collecting has led to a ban on digging in the quarry. Middlehope Shield Mine The Middlehope Shield mine in Middlehope Burn north of Westgate, accessed by an adit called White’s level, is the earliest of the Weardale mines known to produce collector-quality specimens of emerald-green, penetration-twinned fluorite (Fisher, 2006). Records
indicate that the mine was active some time before 1809, and mineralogist Edward Daniel Clarke (1819) made special note of a large find of good specimens there. White’s level penetrated several major ore-bearing veins (including what may be a continuation of the Heights West Cross vein) in the Quarry Hazle sandstone unit just below the Great Limestone formation, and consequently the fluorite specimens are distinctive for having a sandstone matrix. The mine was in operation at least through 1864. Unlike some of the more famous Weardale mines, White’s level was never reopened in the 20th century, and was never described in the mineralogical literature, so it has remained relatively unknown. The workings have since collapsed and the area is now a protected archeological site where collecting is forbidden.
90 • Supplement to the Mineralogical Record, January–February 2010