It is believed to be one of only five in the world and has been valued at $100,000, but a meteorite recently acquired by the Queensland Museum is already proving invaluable to scientists.
The meteorite weighs more than 15 kilograms and is so valuable that it is being held under lock-and-key in a secret location on the northside of Brisbane.
The mass may not look like much from the outside, but luckily the pair who found it while fossicking for gold in northern Queensland realised its value, Queensland Museum mineralogist Andrew Christy said.
“They picked up a large metal mass that was buried — it wasn’t on the surface — about a metre down,” he told ABC Brisbane’s Terri Begley.
“They dug it up, found it was rusty and hence very full of iron — and not a gold nugget like they were hoping for, but probably a meteorite — and brought it into the museum for us to validate.”
Meteorite likely came from the asteroid belt
But it was not apparent just how special the meteorite was until the end was sawed off to reveal a stunning cross-section of metal.
“I was expecting to see solid steely metal, but instead we have this beautiful pattern of finger-y, almost staghorn-coral-like metal crystals,” Dr Christy said.
“[It’s] all very silvery, made out of nickel iron alloy, which are embedded in a bronze-coloured brittle matrix of an iron sulphide mineral called troilite.
“This is quite unusual because most of the iron meteorites that I’ve found are just solid metal.”
Valued at $100,000, the Queensland Museum purchased the meteorite from the discovers with the help of a $50,000 grant from the Federal Government’s National Cultural Heritage Account.
Dr Christy said the meteorite likely came from the asteroid belt between Mars and Jupiter.
“There are lots of much smaller objects — the biggest are only about 1,000 kilometres across — which haven’t gone together to make bigger planets,” he said.
“Some of them have metal cores, like little mini versions of the Earth, and if you gradually blast off through impact all the rock covering that core, eventually you can get chunks of core out.
“Metal meteorites are, we think, little chunks of cores.”
He said the pattern on this particular meteorite indicated it may have come from “the very, very edge of the core, where it was contacting this sulphide material”.
It was the first of this kind of meteorite to be discovered in Australia, and is believed to be the largest of the five known specimens worldwide.
Specimen could help us understand how Earth formed
The museum’s acting chief executive Jim Thompson said meteorites were especially rich in scientific value and Dr Christy is already analysing the specimen using machines like electron microscopes.
“We have much higher magnification images from those that show all these complex and beautiful textures of different minerals and metal alloys … right down to one-thousandth-of-a-millimetre scales,” he said.
“We’ve got chemical analyses and I’ll be weaving those together into a story that might tell us how slowly this thing cooled down from the molten state [and] how different chemical elements distribute themselves between all the different minerals that are in there.”
He said work like this could eventually improve our understanding of how planets like Earth formed.
Part of the meteorite has been on display in the Queensland Museum and is currently in Toowoomba.
It will also travel to Townsville and Ipswich for members of the public to view.