Witherite, Barium carbonate, BaCO3. Gorn mine, Nr. Llanidloes, Central Wales Orefield. Small pieces of witherite, possibly fragments of much larger pieces. The specimens are translucent, and dark cream in colour with no definite crystals observed. However there are parallel growth lines on most pieces found. The specimens were collected from an overgrown sorting floor at the mine.
Marcaste, FeS2. Bryn y Rafr mine, West Wales. Two halves of a broken specimen. The marcasite is in massive form with no crystals apparent, and with a pale yellow colour. This mineral is very susceptible to "pyrite decay" and the specimen is kept in a sealed plastic box with a plentiful supply of silica sachets.
Calcite, Calcium carbonate, CaCO3. Nantiago mine, Central Wales Orefield. Two specimens. The first has interleaved flattened scalenahedral crystals with weathered surfaces. The second is mainly composed of massive calcite adjoining a layer of sphalerite, in which is embedded a fractured rhombohedral calcite crystal with a prominent growth line.
Sphalerite, Zinc sulphide, (Zn,Fe)S. Dylife mine, Central Wales Orefield. Sphalerite in massive form with apparent alignment features. The sphalerite, which is almost black may have derived it's colour from the presence of iron.
Druzy quartz, SiO2. Van mine, Central Wales Orefield. Clusters of small, very fine, well formed druzy quartz crystals. The crystals are clear, and only observable under high magnification.The mine waste heaps, and all mine workings have long since been erradicated by landscaping.