MALACHITE

A carbonate of copper which is bright green in colour. Crystals are rare and usually form in kidney shaped masses. Aggregates normally consist of parallel layers of alternating light and dark green elongated crystals (striped pattern) which have formed at different times. In the finest specimens these stratifications appear as broad curves. Sheen varies from sparkling (adamantine lustre) to silky with great masses tending to have a dull appearance.

It is very beautiful but very soft (3.5-4 on the mohs scale) and not at all resistant to heat which limits its use for jewellery. Bigger slabs are less susceptible to damage than smaller pieces. Treatment may enhance its appearance but will not improve its durability. It is more often used for ornaments such as ashtrays and trinket boxes and in industry as a minor source of copper. In early civilizations people sometimes wore malachite amulets as they believed they would ward off danger and illness. It can also be cut into smooth domed cabochons, which accentuates its green colour and black banding.

Malachite is a secondary mineral which forms by the chemical reaction of pre-existing copper minerals such as chalcopyrite. Rough malachite can be found in rounded masses on the surface of other copper bearing minerals in oxidised zones. It is often found in association with cuprite which is the principal source of copper. In fact most malachite is extracted as a byproduct when cuprite is extracted for copper mining. Its green colouring is readily visible and provides geologists with an indication of where to start digging for copper. It is widely distributed but often found only in small quantities in locations such as Australia, Cornwall (UK), France, Namibia, Siberia and Arizona (US).

MORGANITE

A pink variety of beryl which contains aluminium and beryllium. It is a member of the silicate group and can be any shade of pink, violet, peach or rose due to the presence of manganese. It may appear two different colours depending on the angle from which it is viewed (this is known as dichroism). It has the same properties as beryl apart from its colour (beryl is usually green). It is light, fairly hard (7-8 on the mohs scale) and difficult to melt. Heating can intensify its colour although this effect may fade with time. Crystals are often large.

It was first discovered in California, US and named after J Pierpoint Morgan, the American financier who left his mineral and gemstone collection to the New York Museum of Natural History. It's greatest value is as a gemstone but it also has many properties which are useful in industry. It is similar in appearance to rose quartz, kunzite and red corundum and may be sometimes be mistaken for any of these gemstones if it is a certain shade of pink. However, morganite can be differentiated from these other gems by scientific analysis because its density differs from any of its imitators.

Like all forms of beryl it occurs mainly in granite pegmatites and biotite schists. It may also be found in hydrothermal veins which are created when hot gases from solidifying magma come into contact with the surrounding rock (a process known as pneumatolysis). The St. Petersburg museum in Russia has a beautiful morganite gemstone which was extracted in Madagascar where the finest quality gems can be found. The most recent deposits were discovered in Pakistan. It can also be found in Brazil, Island of Elba, Italy, Mozambique, Namibia, Russia, Zimbabwe and San Diego, California where it was first discovered.