The strange past of the 'magic mineral'

By Zaria GorvettFeatures correspondent@ZariaGorvett

From supernatural capes to sleeping caps, asbestos fibres once had a wide range of bizarre uses.

In the minerals gallery at the Natural History Museum in London, amid rows of ornately carved columns and cathedral-like windows, is an oak display cabinet. Within it is a small clear plastic box, labelled with the warning "DO NOT OPEN".

The case contains what looks like a ball of the grey, fibrous fluff that you might find choking up a clothes dryer – or the kind of thing an owl might regurgitate. It looks like something that has been put on display by accident. But though this artefact is safely sealed within its box, and poses no risk to the public, inside is something deadly. It's an asbestos purse. Oddly, this pale, mangled relic once belonged to none other than American founding father Benjamin Franklin.

For millennia, asbestos was not seen as a deadly hazard – a word now uttered in hushed tones, associated with tragedy and scandal. Instead, it was an exciting, even miraculous, material with highly appealing properties. This is asbestos' past as the "magic mineral", a strange time when it was woven into textiles fit for kings, and used for party tricks. One 18th-Century philosopher even slept in a night-cap made from it.

A valuable acquisition

In 1725, Franklin was not yet the polymath and politician that he is remembered as today. At the time, he was a cash-strapped 19-year-old who had recently been left stranded in London by an unscrupulous employer. Luckily, the plucky teenager had managed to secure a new job at a printing shop, but he needed a quick way to raise some extra funds.

One day, Franklin had the idea of sending the collector and naturalist Hans Sloane a letter, alerting him to the fact that he had brought several curiosities across the Atlantic that might be of interest. Among them was the famous asbestos purse – an item which was seemingly impervious to fire. When it got dirty, it could be thrust into a flame to "purify" it.

Sloane duly summoned Franklin to his house, and the lad was paid "very handsomely" for this noxious item, which eventually ended up at the Natural History Museum.

A material marvel

In fact, the extraordinary fire-resistance of asbestos had been discovered several thousand years before – and has a long history of use in rituals and entertainment.

In the 1st Century AD, the Roman author Pliny the Elder introduced his readers to a new kind of linen, known as "live linen", which could be used to make a variety of quirky products. He had even witnessed its properties himself – napkins which when added to a blazing fire come out cleaner and fresher than before. This same substance, he explained, was also used to make the funerary shrouds for monarchs; because live linen didn't burn, it helped to keep their ashes separated from the rest of the pyre. 

The material was, in fact, asbestos, and by this time, the stories of its properties had already spread across the ancient world. Other sources suggest that it was used for towels, shoes, and nets. One account from Ancient Greece describes a golden lamp made for the goddess Athena, which could reportedly burn for a whole year without going out and had a wick made from "Carpathian flax" – thought to be another name for asbestos.

Pliny believed that his special "linen" was resistant to fire because of its origins in the deserts of India. In this sun-scorched environment, where "no rain is ever known to fall", it became hardened against heat. Later theories included that it was made from the skin of salamanders, which were widely believed to be resistant to fire even in medieval times. Both of these ideas were wide of the mark.

Asbestos is a naturally occurring mineral, and can be found in rock deposits scattered across the globe, from the Italian Alps to the Australian Outback. It can take on many different appearances, depending on its origins and what is being used for, but under a microscope there is one tell-tale sign: stiff, needle-like fibres. Though they may look fragile, these tiny threads are not easily destroyed – they are impervious to heat, chemically inert, and cannot be broken down by biological agents such as bacteria.

In addition to its fire-proofing properties, the resilience of asbestos made it a useful addition to household products, even as early as 2500BC. Back in 1930, archaeologists uncovered ancient pottery buried on the shores of Lake Juojärvi, best known as the cleanest lake in Finland. A later analysis revealed that they had been strengthened with asbestos.

The popularity of asbestos did not diminish, and by the medieval era there was a flourishing trade in this deadly mineral. Charlemagne, who became the first emperor of the Holy Roman Empire in 800AD, was a professional banqueter – feasting his way to diplomatic success. According to legend, he had a snow-white tablecloth spun from asbestos for these occasions, which he routinely thrust into the fire as a party trick.

Asbestos even found its way into warfare. The trebuchet was a war machine used during the Christian crusades, and involved a wooden structure that could catapult flaming bags of pitch or tar at enemy targets. By wrapping the bags of pitch in asbestos, knights could stop them from burning up before they reached their destination. Woven asbestos fibres were also added to suits of armour, where their properties as thermal insulators helped to keep inhabitants warm.

However, it was around the 12th Century that asbestos acquired a more familiar application. In 2014, scientists revealed that they had discovered asbestos fibres in wall plaster behind Byzantine wall paintings in Cyprus.

For most of its history, asbestos was viewed as a highly valuable, even precious material – Pliny attests that, at least in his day, it was more expensive than pearls. But towards the end of the 19th Century, large deposits were discovered in Canada and the United States, and its use exploded. At first, it was used at power plants and on steam engines, but soon the mineral began to creep into people's homes.

The very same properties that had attracted people to asbestos for millennia now encouraged its liberal application wherever fire-proofing, strengthening or thermal insulation was required. By the late 20th Century, the mineral was so widespread that many water pipes were made of it. (Read more about the asbestos found in some drinking water.)

Even in ancient times, there were hints that asbestos was toxic, and with each passing century the risk became clearer. In 1899, an English doctor recorded the first confirmed case of a death linked directly to the material – a 33-year-old textile worker who had developed fibrosis of the lungs.

In the UK, all asbestos was banned in 1999, but much of the asbestos added before this date remains in place – as buildings degrade, it is posing a significant health risk. And it is still in use across much of the rest of the world. The US continues to import asbestos from abroad, though the country's Environmental Protection Agency (EPA) is looking into measures to curb its use. 

Franklin's asbestos purse reminds us that there is still deadly asbestos lurking in even the most unexpected places.

--

If you liked this story, sign up for The Essential List newsletter – a handpicked selection of features, videos and can't-miss news delivered to your inbox every Friday.

Join one million Future fans by liking us on Facebook, or follow us on Twitter or Instagram.

ncG1vNJzZmivp6x7o67CZ5qopV%2BbwrXB0Z5mmqqknrCtsY5rZ2tsYGd9eHnArJmeq6SkwG7Ax55krKyilruosYypmKysXaSzbsDHnmSmmZeesG65yKecq5mc