Fluorite, CaF2 is calcium fluoride and is a halide mineral. In it's pure state it is colourless, and transparent, however it is easily coloured by trace minerals, so clear colourless fluorite is not very common. This specimen is a mass of hundreds of intergrown cubic crystals, and although transparent, it has a slight yellowish colour. The specimen is from Mina Moscona Solis in Spain.
Goethite, a-FeO(OH) and haematite, Fe2O3 are both iron minerals, and are quite difficult to identify from colour alone, because both of them can be found in the same colour range. Haematite, however is more likely to have red colouration. They can be distinguished by crystal form, but unfortunately there are no crystals on this specimen, which is from Merehead quarry in the Mendip hills in Somerset. The quarry was renamed in the mid 1970s as the Torr works, so this specimen was collected before the mid 1970s.
This chalcedony geode is composed of cryptocrystalline quartz and moganite, both of which are varieties of silica SiO2. The chalcedony is almost clear, and the crystalline centre and growth rings can be easily seen. To look at the specimen is almost like looking into a pool of water. The very loose location description is the Sahara desert.
These crystals of quartz, SiO2 are in a formation known as floaters, so named because crystals have formed without being attached to a matrix or host rock. Here are two specimens of which, only one, the bottom one, is a true floater. The upper specimen is mainly composed of crystals grounded in a matrix, with only one floater crystal, the horizontal one. The specimens are from the Huanzalo mine, Huanuco, central Peru.
Both minerals on this specimen are interesting, The specular variety of hematite , Fe2O3 is often referred to by the name specularite. Specular is a reference to the mirror like property of hematite crystals, which on this specimen, are very small. There are many small clear fluorite, CaF2 crystals littered on the surface, with an average size of 2.5 mm. On the rear of the specimen is a much larger and better defined area of specularite, with only a small number of fluorite crystals. The specimen is from the Florence mine, Egremont, in Cumbria, which was the last deep working iron ore mine in Europe, finally closing in 2007 after several changes of operator.