Quartz, SiO2. Cwm Fron mine, Nr. Tylwych, central Wales. At first glance this seam fragment appears to be calcite, but on testing and closer inspection,it is quartz. Very irregular intergrown prismatic crystals, some with darkened cores.
Galena, PbS, Lead sulphide. Eaglebrook ( Nantycagl ) mine, Nant-y-moch reservoir west Wales. Small platelets of galena grown on a thin bed of extremely fine druzy quartz.The bed continues under the small piece of the remaining attached rock indicating that this was once a very narrow vein within the rock.
Calcite, Calcium carbonate, CaCO3. Llanfawr quarry, Llandrindod Wells. From a fault in the quarry this specimen is nothing out of the ordinary, but interesting because it quite clearly shows the typical calcite form and cleavage.
Calcite, Calcium carbonate, CaCO3. Siglenlas mine, Central Wales Orefield. A delicate construction of precipitated calcite coating a piece of host rock, unusual in that it has come from a mine rather than a limestone cave.
Baryte, Barium sulphate, BaSO4. Bryntail mine, Central Wales Orefield. One half of a baryte nodule, broken to reveal massive baryte with a central vugh of small platy crystals. There are also small areas of minute reticulated crystals within the massive body.