Silicide spherules from space fetch astronomical prices at auction
Ever since the Zagami meteorite sold in 1996 at Phillips Auction as crumbs in a vial at $1,538 per gram, the universal appeal of otherworldly rocks was driving the prices of exotic samples sky-high and beyond.
The stellar prices for rocks from space reached new record heights in November when a cosmogenic silicide spherule of Radzinsky Collection provenance, an artifact of the catastrophic cosmic impact of ancient times, was sold for almost $25,000 per gram at Heritage Auction. Cosmogenic silicide spherules were auctioned for the first time to the public.
The previous record price for space-related rocks belonged to Chassignite, a Martian meteorite, sold at Christie’s for $20,000 per gram in February 2022. Ever since the Zagami meteorite sold in 1996 at Phillips Auction as crumbs in a vial at $1,538 per gram, the universal appeal of otherworldly rocks was driving the prices of exotic samples sky-high and beyond.
Spherules of iron silicide are an exceedingly rare mineral, alien to terrestrial conditions and native to carbon stars. They have puzzled scientists since their first discovery in 1859. These enigmatic spherules were considered extraterrestrial until a groundbreaking study published in the peer-reviewed Meteoritics and Planetary Science journal in August 2021 revealed conclusive evidence that iron silicide spherules derive from a vaporized mixture of terrestrial and asteroid materials.
The extreme conditions of condensation in space have turned the vapour of terrestrial impact origin into minerals alien to the geology of Earth, according to the study. Similar minerals are present in rare meteorites, but only as microscopic inclusions. Silicide spherules are the only tangible samples of cosmogenic mineral species that can be seen with the naked eye.
Over 50 occurrences of silicide spherules worldwide have been reported in scientific literature. But large spherules in the range of 5 to 25 mm are exceedingly rare. The combined weight of all silicide spherules collected worldwide since 1859 is under 7 kg, including 4.8 kg from the Ala-Tau site in the Southern Urals.
The ladybug-sized silicide spherule recently sold at auction weighed 0.2 gram sold $6,875 or $24,550 per gram. Fragments of large silicide spherules with a combined weight of 3.5 grams fetched $42,500 or $11,830 per gram.