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A Stone That Can Change Its Colour Right before Your Eyes

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

Collectors all across the globe are willingly paying hundreds of thousands of dollars for some samples of this stone. And the fact the samples they buy may easily lose their attractiveness does not seem to stop them.

Epidote is a mineral that has been given at least a dozen different names through the history of its existence. There is a simple explanation. It was often mistaken for other stones in the past, which is hardly surprising as the mineral’s colour may vary from greenish-black or yellow-green to red or cherry-coloured.

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Фото © Форпост Северо-Запад / Горный музей

The humankind has been aware of epidote since the very ancient times. Back then, the stone was used in magical rituals. Medieval sorcerers picked out large-sized crystals and with their help ‘created portals to other dimensions’. Epidote also has a feature, which was totally incomprehensible to people at the time. If one started turning the mineral in their hand, its colour would be changing. It is known now that epidote crystals can consist of over two hundred facets, and each of them reflects sunrays differently. Hence the effect called pleochroism emerges.

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Фото © Форпост Северо-Запад / Горный музей

There are several varieties of epidote, which are distinguished based on the stone’s colour and some other characters. A well-known one is pushkinite - a version with transparent bottle-green coloured crystals that was first discovered in the Urals. Despite the prevalent opinion, it was named not after Russian poet Alexander Pushkin but after Apollos Musin-Pushkin, a Russian chemist and mineralogist. Pushkinite, thanks to its deep green colour, became a popular gem-cutting material, of which many jewel items were made. Once the Ural mines had run out of reserves, the gemstone, however, went into oblivion.

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Фото © wikimedia.org/Didier Descouens

Nowadays, everyone can admire epidote’s beauty and enjoy examining it with their own eyes instead of pictures. A ledge rock entirely comprised of different mineral’s varieties is located on the Tolstik Peninsula in the White Sea. The rock outcrop extends to more than two hundred metres along the shore. This is a place where such extraordinary natural processes as a transformation of one mineral into another can be observed. Mining in the area is illegal by the way.

Epidote did not become a popular ornamental material or gemstone. It has become popular among followers of non-traditional medicine though. Lithotherapists believe epidote can help with treating headaches, which is done by applying a piece of the stone to the person’s temples and keeping it there for a few minutes.

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Фото © Форпост Северо-Запад / Горный музей

As earlier mentioned, the mineral - particularly because of its high occurrence in nature, modest hardness and processing complexity - is of limited value to jewellers. The same cannot be said about collectors who prefer the most mineral druses. And while jewels with polished stone are comparatively cheap, spectacular crystal clusters may cost a lot. Quite often the price on such specimens only keeps growing with each year, and its final value is determined at auctions.

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Фото © Форпост Северо-Запад / Горный музей

It should be noted that if epidote is not taken proper care of, a sample can lose its colour. For example, the mineral exposed to the direct sunlight gets darker.