Our next publication in the "Stone of the month" column is about May aventurine – a variety of quartz or chalcedony, which is a fine and fine-grained rock consisting of quartz and small scattered scales of various minerals. The mineral belongs to semi-precious and ornamental stones. Its appeal lies in the fact that it has a slight shimmer. There is a legend that in the 16^th century Venetian glass blowers accidentally scattered copper filings into a bowl of molten glass. When the material solidified, it was given the name aventurine, in honour of this accident (avventura – adventure). Only later was the beautiful natural stone named by Europeans in honour of a successful accidental experiment with glass. Aventurescence is the optical effect of light reflecting off mica and hematite plates, creating a mirror-like lustre effect within the mineral. Other names: aventurine quartz, Beloretsky quartz rock, flamboyant quartz, scintillated quartz, imperial stone (in China), mica quartzite. Varieties: Indian jade, aventurine quartzite. The largest deposits of aventurine are found in India, Australia, the USA and Brazil. The gemstone that is mined in the States is called "Colorado Goldstone". It looks something like golden sand, which shimmers in all shades of brown-yellow colour. Avanturine of golden-brown colour and excellent quality is also mined in Russia – in the Southern Urals in the Taganai deposit, as well as in Altai. Since ancient times, the mineral has also been mined in China. The hardness of the stone on the Mohs scale is 6-7.

In addition to natural aventurine, aventurine glass is widely used. In coloured glass, fine filings of oxides of copper, cobalt, iron or chromium are added. By the way, the ancient Egyptians, great masters of glass smelting, learnt to falsify aventurine.

It is not easy to distinguish between aventurine glass and gem stone aventurine – at first glance they are identical to each other. Fake aventurine differs from the real aventurine, first of all, by its very bright sparkle, and the lustres in it are often arranged not chaotically, but in repeating strips, i.e. you can see that they are added there artificially. The glass is also not so hard and scratches are left on it if a piece of quartz is swiped.

Aventurine was popular in ancient Egypt, India and China, where the stone belonged to the group of very expensive and rare minerals. Indian traders brought aventurine to Europe in the Middle Ages, where it became a material for jewellery and crafts.

All types of aventurine are very similar in their composition and physical properties, they differ only in colour. The colouring and optical effect are created by impurities. Aventurine has a characteristic sparkling-golden hue and shimmering lustre due to inclusions of mica, goethite and hematite flakes, as well as cracks filled with iron hydroxides. Avanturine comes only in certain colours: red-brown, grey-yellow, brown, black, green and blue. The colours of this stone are not particularly bright, natural gems are usually pale and slightly cloudy. Many people compare yellow aventurine to a small sun, which everyone can hold in their hands.  And blue, white and green specimens mesmerise with their beauty, which is so similar to the twinkling of stars on a dark night. Red stones always have a much stronger sparkle than green stones. The most suitable shape for aventurine is cabochon. Among other shapes are oval and circle, pear, cushion, heart, trillion. Also, due to the hardness of this mineral, it can be used to make excellent stone-carving products, figurines. Aventurine crystals are rare. Tabular bodies are usually not wide. In addition, ideal from the point of view of craftsmen, homogeneous, areas of mineral are not exceeding 15 centimetres in width. Therefore, there are only a few large pieces of aventurine in the world. The largest aventurine vase can be seen in the Hermitage. It was made at the Yekaterinburg lapidary factory from blocks of aventurine found in 1825 at Taganai. The dimensions of this vase are astonishing – the diameter of the bowl is 246 cm, the height of the vase together with the stem is 146 cm, the total weight is over 4 tonnes. A copy of the 125 cm high aventurine Hermitage vase is stored in the Pavlovsk Palace Museum near St. Petersburg. The third huge aventurine vase is stored in Great Britain. Emperor Nicholas I gave it to the British aristocrat Sir Roderick Murchison (1792–1871), who bequeathed it to the Geological Museum of London.

The therapeutic properties of aventurine are manifested in its ability to cleanse the body and stimulate metabolism. Lithotherapists claim that the stone stabilises the work of the blood circulatory system, preventing the appearance of blood clots, eases the course of inflammatory processes and reduces pain in case of injuries.
Wizards consider the stone to be magical, bringing good luck, increasing self-esteem, charging a person with positive energy. Aventurine zodiacal cycle mascot stone brings good luck to those born in May. The mineral will protect its owner from the evil eye, bedevil and envy. Avanturine is a very fickle talisman as people born under the sign of Gemini from 21 May to 21 June. The power of the mineral will give the owner luck, success at work and improve health.

On the cover: Vanity case with clock (the clock by John Blackwell). Great Britain, London. Circa 1790

Items made of aventurine or its inclusions are presented in the sections of the museum collection "Lapidary works of art and ivories" and "Jewellery".

Kingfisher with a fish. Manfred Wild. Germany, Idar-Oberstein. The 20th century
Ruby snail. Luis Alberto Quispe Aparicio. South America.The20th century
Aventurine bowl. Manfred Wild. Germany, Idar-Oberstein. The 20th century
Young bear with agate ball. Manfred Wild, Emile Becker firm. Germany, Idar-Oberstein. The 20th century
Easter egg "Hen with egg" with detachable brooch in the shape of a cockerel. Manfred Wild, Emile Becker firm. Germany, Idar-Oberstein. The 20th century