Rutile, TiO2 is titanium dioxide, and trimorphous with anatase, and brookite. It is a common accesssory mineral in high temperature, high pressure metamorphic rocks, and in igneous rocks. These specimens were collected by Jim Nicholls, co-founder of the club from Walpole road quarry, Mount Crawford, Australia. The quarry is described as being a kaolin quarry with intersecting quartz veins, which also contain numerous rutile crystals.
Fluorite, CaF2, is also known as fluorspar. This calcium fluoride mineral belongs to the halide family, and is a common gangue mineral in hydrothermal ore deposits. It's crystal form is usually as a cube, often with the cube corners and edges modified, or less commonly as octahedrons. This specimen is from Weardale , north Yorkshire. The light purple cubes are bedded on druzy quartz, and have obviously at one time been completely coated with marcasite, the remnants of which is showing signs of pyrite decay.
Brochantite, Cu4(SO4)(OH)6 is a copper sulphate hydroxide mineral which forms in the oxidising zones of copper deposits. Crystals may be either prismatic or acicular. In this brecciated specimen there are tiny, prismatic crystals in a vhug, and more massive deposits as infills between the various components. The specimen was collected from the Great Orme copper mine, near Llandudno, North Wales.
Chrysocolla is a hydrated copper phyllosilicate mineral which can occur in the oxidation zone of copper ore deposits. The small pieces shown here were collected from the floor of an adit in the Hafod feddgar mine in central Wales. Dr. Stephen Plant of the Russell society is shown inspecting the deposit which has accumulated on walls and floor in the hundred years or so since the mines closure. Care was taken not to touch the main deposits in the mine.
Quartz, SiO2 Druzy variety. The term druzy describes coatings of fine, or small mineral crystals on a base rock, and can be applied to crystals of all minerals. This 22Kg. specimen was collected on the shore line of the Nant y moch reservoir in west Wales, immediately adjacent to the Bryn y rafr mine. The crystals cover about 60% of the host rock, and are mostly white, but with some iron staining.