MADISON, Wis. -

Scientists at the University of Wisconsin-Madison have completed their analysis of a meteorite that struck Wisconsin on April 14, 2010, and are ready to publicly release their findings.

The researchers said the so-called "Mifflin meteorite" created a fireball equivalent of 20 tons of TNT.

Using an electron microscope, researchers found metals in the space rocks connecting the fragments to a piece that scientists said predates Earth's formation.

"So to find metals, that tells us it came from a place where there was not a lot of free oxygen. To me, the metals are the most interesting thing," said John Fournelle, a researcher at UW-Madison.

Combining the existence of metals with evidence of high heat, researchers connected Mifflin's formations to a specific class of space rocks.

"One of the things we learned about the Mifflin meteorite is what kind it is. It's called a l5 chondrite, and the l chondrites are a class of meteorites that have been hitting the earth for 500 million years," said John Valley, a geoscience professor at UW-Madison.

Researchers said the l5 chondrites all came from one astronomical body that formed 4.5 billion years ago.

As to whether the Mifflin meteorite could come from the same l5 chondrite-based meteor as the one that recently hit Russia, scientists said it's still too early to tell.

The meteor in Russia is about 17 times bigger than the Mifflin meteorite.