What is the Most Expensive Material in the World?

No, it’s not a moon rock.

BY CHRIS IMPEY

After a journey of seven years and nearly 6.4 billion kilometers, NASA’s OSIRIS-REx spacecraft landed gently in the Utah desert on the morning of Sept. 24, 2023, with a precious payload. The spacecraft brought back a sample from the asteroid Bennu.

OSIRIS-REx collected a sample from the asteroid Bennu. Photo: NASA

Roughly 227gm of material collected from the 77.6 billion kg asteroid will help scientists learn about the formation of the solar system, including whether asteroids like Bennu include the chemical ingredients for life.

NASA’s mission was budgeted at $800 million and will end up costing around $1.16 billion for just under 255gm of sample. But is this the most expensive material known? Not even close.

I’m a professor of astronomy. I use Moon and Mars rocks in my teaching and have a modest collection of meteorites. I marvel at the fact that I can hold in my hand something that is billions of years old from billions of miles away.

A handful of asteroid works out to $4.7 million per gram or $132 million per ounce. That’s about 70,000 times the price of gold, which has been in the range of $60 to $70 per gram for the past few years.

The first extraterrestrial material returned to Earth came from the Apollo program. Between 1969 and 1972, six Apollo missions brought back 382kg of lunar samples.

A relative bargain

The total price tag for the Apollo program, adjusted for inflation, was $257 billion. These Moon rocks were a relative bargain at $671,000 per gram, and of course, Apollo had additional value in demonstrating technologies for human spaceflight.

NASA is planning to bring samples back from Mars in the early 2030s to see if any contain traces of ancient life. The Mars Sample Return mission aims to return 30 sample tubes with a total weight of 450g. The Perseverance rover has already cached 10 of these samples.

However, costs have grown because the mission is complex, involving multiple robots and spacecraft. Bringing back the samples could run $11 billion, putting their cost at $24 million per gram, five times the unit cost of the Bennu samples.

Some space rocks are free

Some space rocks cost nothing. Almost 50 tons of free samples from the solar system rain down on the Earth every day. Most burn up in the atmosphere, but if they reach the ground they’re called meteorites, and most of those come from asteroids.

Meteorites can get costly because it can be difficult to recognize and retrieve them. Rocks all look similar unless you’re a geology expert.

A chondrite from the Viñales meteorite, from the asteroid belt between Mars and Jupiter. Photo: Ser Amantio di Nicolao/Wikimedia Commons

Most meteorites are stony, called chondrites, and they can be bought online for as little as $15 per ounce (50 cents per gram). Chondrites differ from normal rocks in containing round grains called chondrules that formed as molten droplets in space at the birth of the solar system 4.5 billion years ago.

Iron meteorites are distinguished by a dark crust, caused by melting of the surface as they come through the atmosphere, and an internal pattern of long metallic crystals. They cost $1.77 per gram or even higher. Pallasites are stony-iron meteorites laced with the mineral olivine. When cut and polished, they have a translucent yellow-green color and can cost over $35 per gram.

An iron meteorite. Photo: Llez/Wikimedia Commons

More than a few meteorites have reached us from the Moon and Mars. Close to 600 have been recognized as coming from the Moon, and the largest, weighing 1.8kg, sold for a price that works out to be about $166 per gram.

Mars meteorites

About 175 meteorites are identified as having come from Mars. Buying one would cost about $388 per gram.

Researchers can figure out where meteorites come from by using their landing trajectories to project their paths back to the asteroid belt or comparing their composition with different classes of asteroids. Experts can tell where Moon and Mars rocks come from by their geology and mineralogy.

The limitation of these “free” samples is that there is no way to know where on the Moon or Mars they came from, which limits their scientific usefulness. Also, they start to get contaminated as soon as they land on Earth, so it’s hard to tell if any microbes within them are extraterrestrial.

Scarce elements

Some elements and minerals are expensive because they’re scarce. Simple elements in the periodic table have low prices. Per ounce, carbon costs one-third of a cent, iron costs 1 cent, aluminum costs 56 cents, and even mercury is less than a dollar. Silver is 50 cents per gram, and gold is $67 per gram.

Seven radioactive elements are extremely rare in nature and so difficult to create in the lab that they eclipse the price of NASA’s Mars Sample Return. Polonium-209, the most expensive of these, costs $49 billion per gram.

Gemstones can be expensive, too. High-quality emeralds are 10 times the price of gold, and white diamonds are 100 times the price of gold.

Some diamonds have a boron impurity that gives them a vivid blue hue. They’re found in only a handful of mines worldwide, and at $19 million per gram, they rival the cost of the upcoming Mars samples –- an ounce is 142 carats, but very few gems are that large.

The most expensive synthetic material is a tiny spherical “cage” of carbon with a nitrogen atom trapped inside. The atom inside the cage is extremely stable, so can be used for timekeeping. Endohedral fullerenes are made of carbon material that may be used to create extremely accurate atomic clocks. They can cost $141 million per gram.

Most expensive of all

A 3D model of an anti-matter container. Photo: Shutterstock

Antimatter occurs in nature, but it’s exceptionally rare because any time an antiparticle is created, it quickly annihilates with a particle and produces radiation.

The particle accelerator at CERN can produces 10 million antiprotons per minute. That sounds like a lot, but at that rate, it would take billions of years and cost 3.5 x 10¹⁶ dollars to generate a gram (a billion billion (10¹⁸) dollars per ounce).

Warp drives as envisaged by “Star Trek,” which are powered by matter-antimatter annihilation, will have to wait.