Stonecroft Mine

Also within

Northumberland County

Condition (Natural England)

Geology & landscape

Geological Feature: Igneous Intrusion · Mining / Industrial: Mine Spoil · Rock Type: Limestone

Landscape processes: Volcanic / Igneous

Description

Description The mine waste dumps associated with the former Stonecroft Mine are of interest for the mineralogical specimens they yield. They have also been colonised by a number of nationally rare plant species. Although recently reworked for zinc the dumps on the north side of the Settlingstones Burn still yield good specimens of the rare brown banded form of Sphalerite known as 'Schalenblende'. The locality is of interest for occurrences of the barium zeolite harmotome, in crystals up to 5 millimetres in length associated with calcite and witherite. Harmotome is here thought to occupy the same position in the mineralisation sequence as the double carbonates barytocalcite and alstonite do in mineralisation located within limestone wall rocks as at Blagill Mine near Alston and Fallowfield Mine near Hexham respectively. Harmotome is thought to have developed here and in the nearby Settlingstones Mine because the wall rocks are whin Sill dolerite and a comparison with the Strontian Mine in Lochaber is also merited. The site is therefore not only important mineralogically but also demonstrates the effect of wall rock chemistry on mineralisation. The waste dumps have been colonised by a number of rare plants including the recently discovered Young’s helleborine Epipactis purpurata which is known only from this and one other site, also in Northumberland. Also present are green flowered helleborine Epipactis phyllanthes, broad leaved helleborine Epipactis helleborine, spring sandwort Minuartia verna a species characteristic of lead contaminated soils and common wintergreen Pyrola minor. Each of these species is nationally or locally rare. Other Information 1. This site was previously notified* as part of the Roman Wall SSSI. 2. This site is listed as of national importance in the Geological Conservation Review. 3. Young’s Helleborine is listed as a protected plant in Schedule 8 of the Wildlife and Countryside Act, 1981 statutory instrument No. 288, 1988, Wildlife and Countryside Act, 1981 Variation of Schedules Order 1988. * Under Section 23 of the National Parks and Access to the Countryside Act,1949.

Species mentioned