Did you ever go out with friends as a child and roam around the neighborhood, pretending to look for space rocks? Any time you found something that looked “out of the ordinary”, you would come up with all sorts of ways it could have gotten there, and imagine the far off planet it might have come from. One Australian man could have never dreamed up what he found one day back in 2015 – a valuable rock, but he didn’t know the extent of it.
Believing there might be a gold nugget inside the rock, he brought it home and tried everything he could to open it up, to no avail. Why? Because it was not rock from Earth- it was a rare meteorite .
The rock had a dimpled appearance which, according to geologist Dermot Henry, happens when they pass through Earth’s atmosphere.“They are melting on the outside, and the atmosphere sculpts them.” He explained .
What is a Meteorite?
There are a few steps these “space rocks” have to go through before they become a meteorite. It all begins with meteoroids.
Meteoroids range in size from grains of dust to small asteroids and usually come from larger bodies that have been broken or blasted off. These larger bodies could be comets, asteroids, or even the moon and other planets. They can be rocky, metallic, or a combination of the two. The important thing to remember is that they are only referred to as meteoroids when they are in space .
Next up we have meteors. A meteor is basically a meteoroid that has entered into Earth’s atmosphere at high speeds and burnt up. This is more commonly known as a shooting star. Scientists estimate that about 48.5 tonnes (44 thousand kilograms) of meteoritic material falls on Earth every day . If a meteor survives its harrowing journey through Earth’s atmosphere and actually hits the ground, it becomes a meteorite. Since these rocks travel at tens of thousands of miles per hour, they usually disintegrate under the immense pressure, so only about five percent of the original object will ever make it all the way to the ground .
How Did They Know This Valuable Rock Was a Meteorite?
So how did these Australian scientists determine that Hole’s rock was not from Earth? First of all, it was really heavy, weighing in at seventeen kilograms, or 37.5 pounds .
“If you saw a rock on Earth like this, and you picked it up, it shouldn’t be that heavy,” another Melbourne Museum geologist, Bill Birch, told The Sydney Morning Herald .
They had to use a diamond saw to cut off a small slice of the valuable rock, and found that it contained a high percentage of iron, which makes it an H5 ordinary chondrite . The other telling feature was the number of chondrules throughout the rock, which looked like tiny metallic droplets .
The meteorite, which was given the name Maryborough after the town near it was found, is the third rock of its kind to be found in Victoria [1,3].
What Can We Learn From Meteorites?
Meteorites are more than just simple space rocks. They are one of the cheapest forms of space exploration that give us important clues about the early stages of the solar system [1,4].
They can tell us how smaller bodies came together to form planets, and how our own planet developed after it had formed.
Meteorites provide us with information about the age and composition of various planetary building blocks, how hot or cold the surfaces and interiors of asteroids became, and what levels of impact materials experienced in the past .
“Some provide a glimpse at the deep interior of our planet. In some meteorites, there is ‘stardust’ even older than our Solar System, which shows us how stars form and evolve to create elements of the periodic table.
“Other rare meteorites contain organic molecules such as amino acids; the building blocks of life,” explained Henry . Scientists can figure out how old meteorites are through a process called carbon-dating, and look at their chemical composition, mineral composition, and age to determine where they came from. To do this, they compare the materials the meteorite is made of to the data they have collected about asteroids from earth-based and spacecraft observations . By the same process, they can determine if a meteorite came from the Moon or Mars .
How Do You Know if You’ve Found a Meteor?
It took Hole a few years before he realized he might have something special, and more often than not, when people think they’ve found a space rock, they’re usually wrong. In fact, in his 37 years working as a geologist at the Melbourne Museum, Henry has only ever received two rocks out of thousands that have turned out to be actual meteorites.
So how do you know if you’ve found a meteorite or a meteor-wrong? Here are a few ways you can tell if your finding is the real thing, without a diamond saw to open it up:
The first step is the magnet test. Most meteorites contain large amounts of iron or nickel, so they’ll stick very strongly to a powerful magnet .
The weight of the valuable rock is another possible giveaway. Iron is very heavy, and so the rock should feel much heavier in the hand than one from Earth would normally be .
Many meteorites will have what is called a fusion crust, which is a thin, dark rind that results from the extreme heat and pressure the rock had to go through to get to Earth. As such, these rocks will be much darker than most other rocks around .
Regmaglypts, which are more commonly known as thumbprints, and tiny rivulets called flow lines, will also often be visible on the meteorite’s surface, another symptom of the harsh conditions the rock passed through on its way to the ground .
What Do We Know About Maryborough?
Scientists in Australia have determined through carbon dating that Hole’s meteorite has been on Earth for anywhere from one hundred to one thousand years. Between 1889 and 1951, there have been a number of meteor sightings that could correspond with Maryborough’s arrival on our planet .
It is the second-largest out of only seventeen meteorites that have ever been found in Victoria, Australia, making it far more rare than gold. The journey that little valuable rock has to go through is quite astonishing, which is why it and others like it are such a rare find. As Henry says:
“Looking at the chain of events, it’s quite, you might say, astronomical it being discovered at all.” 
- “Man Keeps Rock For Years, Hoping It’s Gold. It Turned Out to Be Far More Valuable.” Science Alert. Jacinta Bowler. December 2019.
- “Meteors & Meteorites.” Solar System.
- “Maryborough, a new H5 meteorite find from Victoria, Australia.” Publish. William D. Birch, et al. July 17, 2019
- “What We Learn From Meteorites.” AMNH.
- “Meteorite origins.” Meteorites.
- “HAVE YOU FOUND A SPACE ROCK?” Geology.