VOA慢速英语2018--宝石中的隧道可能是生命的标志

Tunnels in Gemstone Might Be Sign of Life

Life has found a way to survive in some of the most extreme conditions in existence. Now, scientists believe they might have found a new habitat for microscopic 1 organisms inside a mineral substance called garnet.

Garnet is a gemstone that comes in many colors, but is most commonly a clear, deep red color.

Recent research found strangely shaped markings inside garnet stones from Thailand. The researchers discovered that fatty acid had collected in the markings. This suggests that an extremely small organism, or microbe, dug the markings into the garnet.

Magnus Ivarsson is the lead researcher on the study. He is with the University of Southern Denmark. He told VOA that the research started with a Thai exchange student named Bongkot Phichaikamjorwut, who was studying the qualities of several pieces of garnet.

The student noticed the strange markings, described as tunnels. These tunnels divided and changed directions. They were unlike the markings caused by environmental damage that she had observed before.

So the student asked Ivarsson for help.

Ivarsson said, “When I first saw these structures, these tunnels, I was sort of intrigued 2 by the complexity 3 of them.”

He added that he had studied other microbial markings in minerals before, but never anything with such complexity.

Garnet is an unexpected habitat for microbes because of how hard the stone is. In fact, Ivarsson suggests that garnet is the hardest mineral ever discovered to have markings created by microbes.

“Who knows what we’ll find next,” he added, “maybe a diamond bored by microbes. Who knows?

Researchers, however, note that no living organisms were discovered within the gemstones. Dawn Cardace is a geosciences researcher at the University of Rhode Island in the United States. She says the study did not find any genetic 4 material, or DNA 5, of the organisms.

But she says that is probably because the researchers would need to examine at least 1,000 garnet gemstones to collect any DNA.

The researchers depended on several technologies to make their findings. They used high-powered microscopes to make three-dimensional maps of the tunnels, which are narrower than a human hair.

The scientists centered their attention on how the tunnels spread and changed directions, as well as the places where the tunnels came together.

Environmental damage can cause breaks in hard materials. But Ivarsson says natural processes cannot explain the complexity of the tunnels his team observed.

To demonstrate that microbes likely created the tunnels, the researchers had to examine the inside of the boreholes.

Ivarsson told VOA, “The organic content tells us that there’s been life living in there.” In fact, the researchers identified organic substances common among bacteria and fungi 6.

The garnets from the study came from the soil in a river near Chiang Mai, Thailand. Ivarsson and his team compared the biological material found in them to other minerals found in the same area, including quartz 7 and hematite. None of the comparable stones showed signs of fatty acids. This suggests that the biological material was unique to the garnet tunnels. Ivarrson says that researchers at least know that biology was involved.

Ivarsson and his team also examined Thai garnets from river soil and from granite 8 rock formations further down the river.

He explains: “When we studied these garnets in the granite, we could see that there were no tunnels. But when we looked at the garnets further down the river, we could see that these tunnels structures had evolved. So, something happened along the way… in the river system."

Shane McClure is the international director of colored stones at the Gemological Institute of America. He says that such changes to the garnets can decrease the value of the stones. One or two small tunnels, he says, do not make a major difference in value.

But he adds if there are many visible tunnels, the value of the gemstone may be greatly affected 9.

The gemstones might not be usable for costly 10 jewelry 11. But the stones do demonstrate that life finds a way in all sorts of unexpected places.

Ivarsson said of the discovery, "When we look for life on Mars, we need to know what to look for. And this … is definitely interesting in the search for life on Mars or any type of extreme environment."

I’m Alice Bryant. And I’m Pete Musto.

Words in This Story

habitat – n. the place or type of place where a plant or animal naturally or normally lives or grows

gemstone – n. a stone that can be used in jewelry when it is cut and polished

tunnel(s) – n. a passage that goes under the ground or through a hill or other material

intrigued – v. made to want to know more about something

bore(d) – v. to make a hole or tunnel in something with a tool or by digging

three-dimensional – adj. having or seeming to have length, width, and depth

fungi – n. a group of living things, such as molds, mushrooms, or yeasts 12, that often look like plants but have no flowers and that live on dead or decaying things

unique to – adj. belonging to or connected with only one particular thing, place, or person

evolve(d) – v. to change or develop slowly often into a better, more complex, or more advanced state

visible – adj. able to be seen