Hackmanite

Origin of Hackmanite

Hackmanite is a relatively ‘recent’ gemstone. Discovered at the end of the 19^th century in Greenland during an expedition led by L.H. Borgstroem, specimens were then studied for years by the Finnish geologist Victor Axel Hackman. In 1901, as a recognition of his work, hackmanite was named after him.

Deposits of better gem quality have since been discovered in Norway, Russia, USA, Canada, Brazil, Afghanistan, and Myanmar.

This gemstone is found in nature in a variety of colours, mainly in different shades of purple, but also violet, pink, grey, and colourless. The hue is often uneven and white veins are common, due to the calcite content.

Hackmanite’s chemical composition makes it a sulphur-bearing sodalite, distinguishable for its fluorescence and tenebrescence effects.

Tenebrescence

Hackmanite’s rarity lies in a fascinating optical property called tenebrescence. This gemstone’s body colour changes when exposed or concealed from certain wavelengths of light. Most commonly, hackmanite turns pink to purple/violet when exposed to ultraviolet radiation. This process is reversed and therefore the body colour fades if the material is exposed to white light sources, either artificial or sunlight. The colour acquired by the gemstones can last for several weeks or months.

Although gemstones are often treated as soon as they are mined, this property can be completely lost if hackmanite is heated above 500°C, this is why oil treatment tends to be the preferred method to improve the clarity of faceted hackmanites. There are not many examples of high-quality faceted hackmanites on the market, most of them are part of institution or laboratory collections. Strands of beads or cabochons are the most common source of hackmanite in jewellery. At times, loose cabochons also come to the market. One of the lots in our Gemstones auction on 23^rd October includes a quantity of these interesting gemstones.

Hackmanite At Auction

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