Editor’s note: The Trivia Geek is on secret assignment for the TechRepublic Community Team for one last week, so we’ve pulled this Classic Geek, which originally ran on March 3, 2004, from our archives to tide you over. Look for the return of fresh Geek Trivia on June 7, 2006.

In mid-February, astronomers made headlines with the announcement that they had confirmed a decades-old astrophysical theory and, in the process, found the largest known “diamond” in the universe. Asteroseismologist Travis Metcalfe was among several scientists who observed the pulsations of the white dwarf star BPM 37093 in the constellation Centaurus to determine that the core of the star actually contained crystallized carbon—not unlike a diamond.

Astrophysicists first theorized in the 1960s that the cores of white dwarfs would crystallize, but only recently have scientists developed the observational and analytical tools necessary to confirm this hypothesis. While BPM 37093 may primarily contain carbon crystal—perhaps a 10 billion-trillion-trillion-carat (1033 carats) crystalline mass measuring 4,000 kilometers in diameter—more than size makes this cosmic rock different from any gem handled by your local jeweler.

The heat and pressure found inside the star, which some astronomers have begun calling “Lucy” in reference to the Beatles song “Lucy in the Sky with Diamonds,” are far more extreme than the mere 2,200 degrees Fahrenheit and 50,000 atmospheres necessary to create either a natural or synthetic diamond. As such, the crystalline structure of Lucy’s core is almost certainly unlike any diamond on Earth, and it probably deserves a whole new mineralogical classification.

Still, space-originating diamonds are hardly unknown to science. Various meteorites and their associated earthly craters have harbored diamonds, though the crystalline structure of many of these diamonds is quite extraordinary. While the majority of terrestrial diamonds sport octahedronal or dodecahedronal crystalline structures, scientists have also found some meteorite diamonds with hexagonal structures, which qualified for their own mineral designation, lonsdaleite.

While meteorite diamonds still present several geological mysteries, some diamond scholars suggest that meteorite strikes may have contributed to the creation of the largest terrestrial diamond ever recovered.

WHAT IS THE LARGEST DIAMOND EVER RECOVERED ON EARTH?

What’s the largest diamond ever recovered on Earth, a terrestrial crystal that may trace its origins back to meteorite strikes that litter the geological record?

The Brazilian carbonado diamond Sergio holds this distinction, weighing in at 3,167 carats—nearly 1.4 pounds (0.64 kilograms). This outweighs even the famous 3,106-carat Cullinan diamond, from which the Great Star of Africa centerpiece of the British crown jewels originated.

So why have you probably heard the Great Star of Africa cited as the world’s largest diamond, and not Sergio? At 530.2 carats, the Star of Africa is the world’s largest cut and polished diamond. A jeweler broke the original uncut Cullinan diamond into dozens of finished and unfinished gems, including the Star of Africa.

Sergio is not only uncut, but it’s unusual in that it’s a carbonado (from the Portuguese word for burned) diamond. Carbonados resemble black igneous rock far more than the conventional clear or translucent diamonds affixed to many an engagement ring. In fact, it’s unlikely that anyone other than a trained geologist would be able to casually recognize that a carbonado is any relation to a diamond, even though it’s essentially the same crystallized carbon found in the more familiar versions of the gem.

Atomic isotope dating suggests that carbonados are anywhere from one to four billion years old, placing their origins in the Precambrian Era of constant meteor impacts. However, their specific isotopic composition and current geologic locations have led to a host of contradictory theories about the origins of carbonado diamonds.

Many of these hypotheses suggest that carbonados form in or because of meteorites that crashed to Earth eons ago. But the most daring theory suggests that carbonados are the product of exploding red giant stars, where stellar shockwaves fused carbon into these unique diamonds and then hurtled them toward Earth, where they fell as meteorites.

While science is a fair distance from determining which, if any, of these theories is accurate, one thing is certain: Every few billion years, riches really do fall from the sky.

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The Quibble of the Week

If you uncover a questionable fact or debatable aspect of this week’s Geek Trivia, just post it in the discussion area of the article. Every week, yours truly will choose the best post from the assembled masses and discuss it in the next edition of Geek Trivia. (To see the original quibble from this article, see Listing A.)

This week’s quibble comes from the April 19 edition of Geek Trivia, “Stationary perspective.” TechRepublic member Bill had some useful addendums to the subject of early space station concepts.

“[I] found an excellent PBS page that outlines the first mentions of a space station. A couple quotes from there:

“‘The first person to offer a blueprint for a functional space station was Russian schoolteacher Konstantin Tsiolkovsky, who designed a cylindrical facility with a greenhouse, laboratory, living quarters, and docking area for spacecraft. His didactic novel Beyond the Planet Earth (1920) remarkably anticipated the ISS by picturing a space station with a crew of six people from Russia, America, France, England, Germany, and Italy, all of which (save for England) are now involved in its construction.’

“Also: ‘Murray Leinster’s The Power Planet (1931) proposed space stations as sources of energy for Earth; Basil Wells’ Factory in the Sky (1941) demonstrated the potential benefits of space factories; and George O. Smith’s Venus Equilateral stories (1942 to 1945) featured an inhabited communications satellite. In effect, science-fiction writers critically examined the concept of space stations and concluded that they would be practical and helpful in various ways.’ As always, sci-fi writers lead the way.”

Indeed they do, dear reader. Thanks for the info, and keep those quibbles coming!

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The Trivia Geek, also known as Jay Garmon, is a former advertising copywriter and Web developer who’s duped TechRepublic into underwriting his affinity for movies, sci-fi, comic books, technology, and all things geekish or subcultural.