Pyromorphite

Pyromorphite

Pyromorphite,  Pb5(PO4)3Cl   is Lead Chloride Phosphate.  One of the secondary lead minerals found in the oxidised zone of lead ore deposits. The hexagonal barrel shaped crystals can vary in shape from thin and elongate, to short and stubby. The colour may also vary, but usually pale green to deep green. This specimen is from Caldbeck in Cumbria, and is a disorganised mass of elongate, pale green crystals.

Azurite

Azurite

Azurite,  Cu3(CO3)2(OH)2  is a copper carbonate often found in association with malachite, which is chemically similar. Both minerals are found in the weathering zone of copper ores, with malachite being the predominant mineral. The specimen is mostly malachite with inclusions of Azurite, both in massive form, and no observable crystals. The specimen was collected at the Burra Burra mine, Burra, South Australia.

Rutile

Rutile

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

Fluorite

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

Brochantite

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.