Calcie, calcium carbonate, CaCO3. Calcite comes in so many forms, that most specimens have an appearance that can be attributed to a particular location. This specimen from St Austell in Cornwall is no exception It has an appearance that I have not seen at any other location.The prismatic druzy crystals are very creamy in colour, They are very tightly packed, and are growing from a base of massive translucent calcite.
Haematite, Fe2O3, iron oxide, and the main ore of iron. These specimens were collected from Mine Train quarry in the Forest of Dean. They were picked up from one of the heaps in the quarry. The ore in situ is shown in the inset photograph. This form of haematite is known locally as "Brush ore" because of it's obvious likeness to the bristles of a brush, as in the inset photograph.
Calcite, calcium carbonate, CaCO3. Another specimen of calcite collected many years ago, when I visited several south Wales quarries with the Russel Society. This specimen, which came from Taff's Well quarry is a very nice cream coloured, twinned crystal sitting on a bed of small brown druzy crystals.
Siderite, Iron carbonate, FeCO3. This mineral is fairly common throughout the Central Wales orefield. This specimen is from Geufron mine, on the edge of the Hafren forest, near Llanidloes. It is composed of closely packed crystals, with very few that are exposed to view. Those that are, as in the inset picture, have a slight curvature on the crystal faces, which helps to identify the mineral. The Geufron mine waste heaps are a good source for copper secondary minerals.
Calcite, Calcium carbonate, CaCO3. This specimen is a fine cluster of creamy nailhead crystals on a limestone matrix. I collected it from Ton Mawr quarry at Pentyrch, near Cardiff.