The epitome of a transitional Seymchan pallasite. 323 x 138 x 3mm (12.75 x 5.5 x 0.1  in) and 321g (0.75 lbs). Estimate $7,000-10,000. Offered in Deep Impact Martian, Lunar and Other Rare Meteorites,

An expert’s guide to meteorites

Extraterrestrial rocks that fall to Earth are extremely rare and can be extraordinarily beautiful. Dr Alan Rubin, a cosmochemist at UCLA, explains their origins, with examples offered online until 23 February 

Meteorites are small rocks from space that impact the Earth. They are exceedingly rare — the collective weight of every meteorite known to exist is less than the world’s annual output of gold. 

The vast majority originate from the ‘asteroid belt’ and hail from 100 - 150 different asteroids. A few hundred meteorites come from the Moon and Mars too; they were ejected by energetic collisions into interplanetary space where they eventually assumed Earth-crossing orbits. 

Asteroid meteorites are the oldest rocks around — a few hundred million years older than the oldest existing Earth rocks, and approximately 60 million years older than the Moon itself.

Imilac — mantle-core boundary of an asteroid revealed. 228 x 171 x 3mm (9 x 6.75 x 0.1  in) and 401.7g (0.75 lbs). Estimate $10,000-15,000. Offered in Deep Impact Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
Imilac — mantle-core boundary of an asteroid revealed. 228 x 171 x 3mm (9 x 6.75 x 0.1 in) and 401.7g (0.75 lbs). Estimate: $10,000-15,000. Offered in Deep Impact: Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online

There are three main varieties of meteorites

Stones (95 per cent of meteorite falls): these are silicate rocks (some resembling terrestrial volcanic rocks) derived from melted and unmelted asteroids, the Moon, and Mars. Some were melted in their parent bodies; in others one can discern the raw ingredients of the planets. Some stones may have brought water and organic compounds to the Earth, facilitating the origin of life.


Matchless stone meteorite — an artefact of early solar system history. 228 x 273 x 119mm (9 x 10.75 x 4.66  in) and 8.974 kg (19.75 lbs). Estimate $50,000-80,000. Offered in Deep Impact Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
Matchless stone meteorite — an artefact of early solar system history. 228 x 273 x 119mm (9 x 10.75 x 4.66 in) and 8.974 kg (19.75 lbs). Estimate: $50,000-80,000. Offered in Deep Impact: Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
Stone meteorite sphere – NWA 869. 59mm (2.33  in) in diameter and 399.2g (0.75 lbs). Estimate $1,600-2,400. Offered in Deep Impact Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
Stone meteorite sphere – NWA 869. 59mm (2.33 in) in diameter and 399.2g (0.75 lbs). Estimate: $1,600-2,400. Offered in Deep Impact: Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online

Irons (4 per cent of falls):  these are metallic iron-nickel masses, predominantly from the cores of melted asteroids.


Gibeon meteorite — singular exotic sculpture from outer space. 404 x 295 x 176mm (16 x 11.5 x 6.75  in) and 61.05 kg (134.5 lbs). Estimate $200,000-300,000. Offered in Deep Impact Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
Gibeon meteorite — singular exotic sculpture from outer space. 404 x 295 x 176mm (16 x 11.5 x 6.75 in) and 61.05 kg (134.5 lbs). Estimate: $200,000-300,000. Offered in Deep Impact: Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
Sikhote-Alin meteorite — from one of the largest meteorite showers in human history.  88 x 62 x 29mm (3.5 x 2.5 x 1  in) and 375.3g (0.75 lbs). Estimate $1,000-1,500. Offered in Deep Impact Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
Sikhote-Alin meteorite — from one of the largest meteorite showers in human history.  88 x 62 x 29mm (3.5 x 2.5 x 1 in) and 375.3g (0.75 lbs). Estimate: $1,000-1,500. Offered in Deep Impact: Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online

Stony irons (1 per cent of falls):  these half-stone, half-metal samples are formed on or within melted asteroids by the mixing of metal core material with silicate rocks. One class of these meteorites, the pallasites, are widely considered the most beautiful extraterrestrial substance known.


Fukang — cut and polished end piece of the most beautiful extraterrestrial substance known. 127 x 112 x 74mm (5 x 4.5 x 3  in) and 1.870 kg (4 lbs). Estimate $50,000-80,000. Offered in Deep Impact Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
Fukang — cut and polished end piece of the most beautiful extraterrestrial substance known. 127 x 112 x 74mm (5 x 4.5 x 3 in) and 1.870 kg (4 lbs). Estimate: $50,000-80,000. Offered in Deep Impact: Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
Marjalahti — notable offering of an extremely rare witnessed pallasite fall. 59 x 99 x 18mm (2.33 x 4 x 0.75  in) and 139.94g (0.33 lbs). Estimate $18,000-25,000. Offered in Deep Impact Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
Marjalahti — notable offering of an extremely rare witnessed pallasite fall. 59 x 99 x 18mm (2.33 x 4 x 0.75 in) and 139.94g (0.33 lbs). Estimate: $18,000-25,000. Offered in Deep Impact: Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online

Meteorites have been pelting the Earth throughout geological history. Sixty-six million years ago, an asteroid (essentially a giant meteorite) slammed into the Yucatán Peninsula in Mexico, causing a mass extinction that wiped out the dinosaurs. Had that meteorite missed, there would be no cows, cats, pigs or people on this planet right now. 

Some stone meteorites are known to contain hundreds of organic compounds including amino acids, the building blocks of proteins. Many scientists believe the Earth provided a suitable environment for life to commence after meteorites and comets brought water and organic material to the planet’s surface. Had it not been for these extraterrestrial wanderers, there may have been no life on Earth at all.


Winchcombe meteorite — the leftover ingredients of the recipe of life. 17 x 16 x 9mm (0.66 x 0.66 x 0.33  in) and 1.737g (8.5 carats). Estimate $5,000-8,000. Offered in Deep Impact Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
Winchcombe meteorite — the leftover ingredients of the recipe of life. 17 x 16 x 9mm (0.66 x 0.66 x 0.33 in) and 1.737g (8.5 carats). Estimate: $5,000-8,000. Offered in Deep Impact: Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online

Although there are 64,000 meteorites in the world’s collections, about two-thirds will never be available to the general public. And the resource is barely growing: each year hunters recover only about eight to ten fresh falls and a few hundred weathered non-Antarctic ‘finds’ (most of which weigh less than 200 grams). 

For scientists to classify a meteorite into the proper category, the rock must be broken or cut; only then can well-characterised samples be offered for sale. Meteorite hunters, meteorite researchers, and meteorite dealers work together in a worldwide enterprise to discover new specimens, uncover details about the origin of the solar system, and make samples available to the discerning collector. 

 

Lunar meteorites

Specimens of the Moon are among the rarest substances on Earth. Less than 650 kg of lunar meteorites are known to exist. All would fit within five footlockers and a significant portion of these precious samples are controlled by governmental institutions. Only about 0.6 per cent of known meteorites are lunar; in fact, they are so scarce that, to date, none have been found in Europe, Asia, North America or South America.

NWA 5000 — a complete slice of the Moon. 193 x 178 x 60mm (7.75 x 7 x 0.25  in) and 406g. Estimate $200,000-300,000. Offered in Deep Impact Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
NWA 5000 — a complete slice of the Moon. 193 x 178 x 60mm (7.75 x 7 x 0.25 in) and 406g. Estimate: $200,000-300,000. Offered in Deep Impact: Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online

Scientists identify moon rocks by their specific textural, mineralogical, chemical and isotopic signatures. Lunar meteorites are ‘breccias’ — stones made of broken rock fragments, glass shards and glass spherules cemented together by interstitial impact melt. They are derived from the near-surface regions of the Moon; this is the lunar regolith – the layer of impact-fragmented and pulverized rock and mineral grains that overlies lunar bedrock.

NWA 12691 — rare lunar sphere. 42mm (1.66  in) in diameter and 109.8g (0.25 lbs). Estimate $18,000-25,000. Offered in Deep Impact Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
NWA 12691 — rare lunar sphere. 42mm (1.66 in) in diameter and 109.8g (0.25 lbs). Estimate: $18,000-25,000. Offered in Deep Impact: Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online

Some lunar meteorites are identical to moon rocks collected by the Apollo astronauts. The light-colored, heavily cratered regions of the Moon are called the ‘lunar highlands’; they are made up mainly of anorthosite — a light grey rock rich in calcium-aluminum silicate. The dark regions of the Moon are the ‘maria’ — impact basins that were flooded with basalt, a dark grey volcanic rock.

Martian meteorites

Mars’ heavily cratered southern hemisphere attests to its bombardment by asteroids; the relatively low surface gravity of the Red Planet (only 38 per cent as strong as the Earth’s) suggests it would be feasible to launch rocks during a giant impact. But there was no proof that Martian meteorites had actually landed on Earth until 1983, when NASA scientists analyzed the gas bubbles trapped inside impact-melted glass within a basaltic meteorite found in Antarctica. The chemical and isotopic composition of those bubbles precisely matched that of the atmosphere measured on the surface of Mars by the Viking spacecraft lander in 1976. 

The putative Martian basalts have relatively young crystallization ages (180 million to about 2 billion years before present); this shows that these rocks cannot be from asteroids because those small bodies had cooled completely more than four billion years ago. The case for the Martian origin of these rocks is essentially closed, since even the most sceptical meteorite scientists would probably admit that there is at least a 95 per cent probability that these samples are from Mars.


NWA 12690 — the third largest piece of Mars on Earth. 233 x 244 x 154mm (9 x 9.66 x 6  in) and 9.085 kg (20 lbs). Estimate $500,000-800,000. Offered in Deep Impact Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online
NWA 12690 — the third largest piece of Mars on Earth. 233 x 244 x 154mm (9 x 9.66 x 6 in) and 9.085 kg (20 lbs). Estimate: $500,000-800,000. Offered in Deep Impact: Martian, Lunar and Other Rare Meteorites, until 23 February 2022, Online

Although there are close to 200 Martian meteorites in collections worldwide, many of the specimens are actually different pieces of the same rock. A good estimate of the number of separate Martian meteorites is 135, which provide scientists unparalleled access to evidence bearing on the geological history of the Martian crust. These rocks are scientifically important, commercially valuable, and a key component of fine collections.

Dr Alan Rubin is a researcher at the Department of Earth, Planetary, and Space Sciences at UCLA and researcher-curator of the university’s Meteorite Collection