Quartz, SiO2. Llawr y Glyn, Nr. Staylittle, central Wales. This unremarkable specimen is included in my collection simply because it was one of my earliest collected specimens over twenty years ago. The specimen simply fell out of a roadside embankment, unusual because the nearest mine workings are about two miles distant, perhaps indicative of an undiscovered mineral lode close by.
Pyrite, FeS2, and Dolomite, CaMg(CO3)2. Tan y Foel quarry, Nr Adfa. central Wales. Minute cubic crystals of pyrite deposited on larger cubic crystals of dolomite. Two groups of crystals,some are brassy yellow and definitely pyrite, and some are almost black and possibly magnetite.
Calcite, calcuium carbonate, CaCO3. Creigau quarry, near Cardiff, south Wales. A collection of twinned scalenahedral crystals of calcite interspersed with much smaller nail head crystals. All the crystals have acquired a coating of a reddy brown colour, probably with an iron content. Close to where this specimen was collected was a five foot cavity in the quarry wall, completely lined with even larger crystals, but impossible to recover without catastrophic damage.
Hemimorphite, Zn4(SiO7)(OH2).H2O. Henfwlch mine, west Wales. The beauty of the hemimorphite crystals in these specimens can only he appreciated under a microscope. The Henfwlch mine is noted for the presence of hemimorphite, which is a zinc ore found in the weathering zones of sphalerite deposits. See hemimorphite 2 for more specimens.
Hemimorphite,Zn4(Si2O7(OH)2.H2), Henfwlch mine, West Wales. When these specimens of hemimorphite are observed under the microscope sprays of radiating bladed clear crystals can be seen. Also common at this mine are microcrystalline globules which can just about be seen in the centre left pocket, and the top and bottom right pockets. When I can arrange it I will update this entry with better photographs. Each pocket measures 6cm by 4.5cm.