Galena, Lead sulphide, PbS. Pen y Gaer hill, Llanidloes, Central Wales Orefield. This specimen was obtained from a very small trial, not known as a mine. It is about 80% galena with the rest being quartz. The galena is very finely cleaved and is better observed under a microscope. The quartz is a very fine aggregate intermixed with galena.
Hafod Feddgar mine, Central Wales Orefield. The mine, having been closed for about 100 years, has given time for copper solution to stain leached calcite on the walls and floor of the adit. Not wishing to disturb the main body of interest, this specimen was taken from the floor close by. It is brecciated rock with precipitated calcite on the surface, coloured by copper solution leaching from the roof.
Goethite, Iron oxide hydroxide, FeO(OH). Aberdaunant mine, Nr. Llanidloes, Central Wales Orefield. An encrustation with no visible crystals on brecciated rock of quartz and host rock. The goethite is slightly mammillary in appearance in places.
Quartz, SiO2. Pencurig mine, Dylife, Central Wales Orefield. These specimens were taken from the wall of an adit. I have labelled them as unclassified because of their peculiar nature. The quartz appears to be fractured and friable, and can be easily broken by hand. Friable quartz can be found as a sedimentary deposit, but this quartz is from a hydrothermal source.
Hydrozincite, Zinc bloom, Marionite, Zn5(CO3)2(OH)6. Pencurig mine, Dylife, Central Wales Orefield. The specimens were recovered from the floor of an adit, perhaps taking about 100 years to form since closure of the mine. Hydrozincite is also known as zinc bloom or marionite, and is a zinc carbonate. These specimens have a substantial coating, which is very white, and vitreous in appearance.