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A Stone Tank Armour Is Made Of

Joint project of St.-Petersburg Mining museum and Forpost Nord-West.
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Фото © Форпост Северо-Запад / Горный музей

There are not many people who know this mineral exists. It is hardly known on the gem market as well, with a rare jeweller being able to tell it from a diamond.

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Фото © wikimedia.org

In Russia, phenakite is also known as a ‘Ural diamond’, for the stone was first discovered two centuries ago in the Ural region, at the deposit known as Изумрудные копи Урала (‘Ural Emerald Mines’). At describing phenakite, mineralogists gave it a funny name. It comes from Ancient Greek φέναξ meaning ‘deceiver’. As geologists say, the mineral received such name due to its close similarity to quartz, apatite, topaz, and some other stones. The most valuable feature phenakite has is, however, its lustre that leaves behind the glare of the world’s most famous and expensive gemstones. In fact, this stone’s property was of very high interest to jewellers ever since the phenakite had been found. As such, Carl Fabergé organised expeditions to the Ural to get a hold of this stone and make it a part of his exquisite jewel items.

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Фото © Форпост Северо-Запад / Горный музей

The mineral is usually colourless, but pink, yellow, cyan, and brown samples occur too. For a long time, mineralogists had no idea phenakite could lose its colour and then restore it. In the middle of the 19th century, a yellow-pink sample of cut phenakite was exhibited at the Paris World Exposition, which surprisingly turned transparent two months after the exhibition. Luckily, stone’s colour got partially retrieved by placing the specimen into a dark room and leaving it there for a few days.

Alexander Fersman, Russian geochemist, believed phenakite to be a high-profile gemstone and supposed it would become a real success on the jewellery market. Yet the mineral is now mainly sought out by collectors since its fragility negatively affects cutting possibilities.

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Фото © Форпост Северо-Запад / Горный музей

Nevertheless, there are areas of use for phenakite outside of collecting and jewellery. Phenakite mined in the Urals was particularly highly valued during the years of industrialisation in the USSR. Back then the stone was a primary raw material component needed for producing beryllium, with the latter still keeping its status of a strategic metal for the country. In the 30s, beryllium along with alloyed steel and nickel were made use of to make tank armour. Nowadays, various systems of modern tanks are covered with beryllium to improve protection without adding further weight to them. Beryllium made of phenakite is more durable than steel, three times lighter than aluminium; it can as well withstand sudden temperature drops. Therefore, spaceship building is another area of application for it.

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Фото © Форпост Северо-Запад / Горный музей

Although phenakite is mined in different regions of the world, the amount of extracted mineral is very modest. And because of it, phenakite of gem-quality is not only a rare find but also an expensive one. The most valuable specimens are thought to be those that are mined in the Urals. Samples reaching over seven centimetres in size can be found there. The most highly-priced stones are of vibrant dark-red colour.

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Фото © Форпост Северо-Запад / Горный музей

Anyone can see now for themselves how phenakites are mined and how the extraction, sorting and storage processes are organised. Excursions are arranged at Мариинский прииск (‘Mariinsky Priisk’) mine located in the Ural.

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Фото © wikimedia.org