A huge 100-kg rock used by a Spanish farmer for more than three decades to press ham has turned out to be an asteroid worth a whopping $5.3 million.

Faustino Asensio Lopez found the massive rock — measuring 18x25x8 inches — in 1980 while he was tending to livestock with his father in a field near Ciudad Real.

Believing the rock to be military scrap from the country’s civil war, his family members used it to cure meat for over 30 years, New York Daily News reported.

However, it was only in 2011 when Lopez saw a TV report on meteorite sightings over Spain that he got in touch with geologist Juan Carlos Gutierrez Marco.

Extensive analysis confirmed the rock to be a prehistoric metallic meteorite — a solid piece of debris from an asteroid or comet that survives impact with the Earth’s surface.

According to the Spanish newspaper ABC, it is the fourth such meteorite to have been found in Spain.

Previously, meteorites were found near Quesa, in 1898, near Granada in 1912 and near Zaragoza in 1950.

“The object remained buried and [as a result], survived the times of the most demand for metals,” said Mr. Marco.

Earlier this week, Madrid’s Mining Museum opened a display featuring a fragment that was broken off for testing. It is alongside a replica of the original, the report said.

The Arthur Ross Hall of Meteorites is also home to a similar asteroid — the Gibeon meteorite found in 1836 in Namibia.

More In: Science | Sci-Tech | News