Silicide Spherules from Space Fetch Astronomical Prices at Auction

LONDON, Dec. 7, 2023 /PRNewswire/ -- 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, the Holy Grail of Martian meteorites, 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 $1538 per gram, the universal appeal of otherworldly rocks was driving the prices of exotic samples sky-high and beyond. Extreme rarity is the primary but not the only reason why the choicest pieces of space debris command the highest prices. Scientific significance, history, and tell-tale features of the composition add significantly to the value and demand.

Is there an intrinsic value in silicides? Spherules of iron silicide, an exceedingly rare mineral, alien to terrestrial conditions and native to carbon stars, have puzzled scientists since their first discovery in 1859. These enigmatic spherules with signs of ablation in fiery aerial flight, found in sedimentary rocks of various geological ages, seemed out of place on Earth. They 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 study showed that silicide spherules recovered at the Ala-Tau range in the Southern Urals are a product of a vapor plume ejected into space as the result of an asteroid impact of catastrophic scale over 300,000 years ago. In the cold of space, the ejected gas condensed into spherules composed of cosmogenic mineral species. "The extreme conditions of condensation in space have turned the vapor of terrestrial impact origin into minerals alien to the geology of Earth"- explains the co-author of the research paper, Dr. Gulbin of the Mining Institute of St. Petersburg. Similar minerals are present in rare meteorites. But only as microscopic inclusions. Meanwhile, silicide spherules are the only tangible samples of cosmogenic mineral species available to appreciate with the naked eye.

For scientists, the composition of silicide spherules offers a glimpse into a large-scale cosmic impact capable of delivering ejecta to space. "Vapor plume ejection to space has been a neglected aspect in science of impact studies. Iron silicide spherules offer a first-hand perspective into neglected phenomena"- says the lead author of the study, Sergei Batovrin, who found silicide spherules in the Ural Mountains. In the eyes of his colleagues, an iron silicide spherule is no less than the Rosetta Stone for deciphering the history of cosmic impact disasters. The presence of silicide spherules in hard sediments of various ages on four continents indicates that cosmic impacts of catastrophic magnitude are far more frequent in geological history than suggested by evidence of cratering discovered so far. For collectors, silicide spherules are probably the only opportunity to touch an artifact from the cosmic calamity of a grand scale.

However, silicide spherules are not easy to come by. Over 50 occurrences worldwide were reported in scientific literature. But most samples are sub-millimeter in size and difficult to recover by drilling at significant burial depths in hard-rock sediments. 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 7kg, including 4.8kg from the Ala-Tau site in the Southern Urals. These samples are locked in research institutions. Only 250 grams are in private hands. No wonder, that a ladybug-sized silicide spherule of 0.2 gram with Radzinsky Collection provenance sold at Heritage Auction for $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. The lower price realized for spherule fragments was still way higher than the legendary $10,000 per gram price-point of the famous Martian meteorite NWA 7034 nicknamed "Black Beauty".

RADZINSKY COLLECTION
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SOURCE Radzinsky Collection