Mineral mania; scientists crack the case of a masquerading, true-blue mineral.

If you bought a hunk of blue rock at a souvenir shop, took it home for rigorous study, and found no mention of it in the most well-known encyclopedias, you'd announce your find to the world. You'd tout your discovery like it was gold!

That's just what a sharp, young British geologist named Anna Grayson did. The blue rock she discovered - the size of a brick and the weight of a kitten - appeared to be an entirely new mineral, one of the basic materials that makes up Earth. Eureka!

But sometimes good science works in strange ways. Now, armed with the results of dozens of tests conducted with the latest high-tech instruments, scientists have a different angle on the mysterious blue stone. Minerals exactly like it have been seen before, as far back as the late 1800s. But back then, most people thought the "minerals" were fake. No one paid any attention to the vivid blue stone - until now.

MINERAL MYSTERY

The twisted tale goes like this: Fifteen years ago, Grayson nabbed the blue stone at a roadside rock shop in Morocco. She was drawn to its magnificent color, but she knew it was misidentified. The label read, "Lapis lazuli," a blue stone used to make jewelry.

"It was clear to me that this wasn't lapis," Grayson says. "It was the wrong hardness, the wrong texture. Lapis always has flecks of `fool's gold,' and this didn't."

Grayson brought the exotic specimen home to London, hoping to identify it. For years, she toted her rock to university labs. Scientists scratched the sample - and then scratched their heads. No one could tell her what it was. Some scientists even suspected that Grayson had dyed the rock.

Then last spring, Grayson stopped by London's Natural History Museum. A mineralogist named Gordon Cressey agreed to run the rock through a battery of tests, first to determine whether it was a mineral, and if so, which one?

TESTING, TESTING

To identify the rock as a mineral, Cressey had to prove that the specimen was: naturally occurring; inorganic (nonliving); and a solid with a distinct chemical composition and crystal structure.

By viewing a paper-thin slice of the rock under a microscope, Cressey could see that the specimen was made of natural igneous rock, a type of rock formed by the cooling of hot, semiliquid magma within Earth's mantle. He could also tell that individual atoms of the rock linked to form flat-sided, repeating patterns - crystals!

Bombarding the sample with a beam of energy helped reveal the sample's chemical composition. That's because atoms of different elements absorb and give off different amounts of energy. Cressey identified calcium, iron, aluminum, magnesium, silicon, and oxygen. Because he found no cells or remnants of living things, he concluded that the rock was inorganic. Together, these clues combined to say, "You've got a true-blue mineral here!"

But which mineral? Cressey was still puzzled. He decided to investigate the mineral's physical properties (its outward characteristics) to see if they matched any other known mineral.

Most striking, of course, was the mineral's vivid blue color. Where did it come from?

"On a very simple level," Cressey says, "the color usually comes from the elements present in the mineral." In this case, the color culprit turned out to be iron. Apparently, iron atoms in the crystals absorb yellow, green, and red light, but reflect the blue part of the spectrum. So the mineral appears to be a brilliant blue.

Was the color natural? To find out, Cressey viewed a slice of crystals under a microscope. When he shined a light from different directions, Cressey noticed the crystals' color changed from blue to cream to clear. When he shined the light parallel to the crystals, they remained blue. Dyed crystals wouldn't do that, Cressey says.

Cressey also studied the mineral's hardness, its ability to resist being scratched, and its luster, or ability to reflect light. Unlike lapis lazuli, "this mineral won't shine if you polish it," Cressey discovered.

Armed with these clues, Cressey tried to locate the mineral on an international database that catalogs roughly 3,700 known minerals. Not a single one matched. Grayson's mineral was new!

That's when the newspapers got hold of the story and the scientific community went wild. But before Grayson and Cressey could name their new find, they discovered they'd made a monumental mistake.

FAKE OUT?

Just as stories of the new blue mineral hit the newsstand, one of Cressey's colleagues showed him a long-lost scientific paper. The paper desciibed the "new" mineral to a tee. Apparently, scientists first discovered the mineral in 1876 and called it arenite, which means "blue sky" in Greek. However, like the modern scientists that Grayson first encountered, 19th-century scientists assumed the mineral was a fake because of its unbelievable color. "It's like giving someone a blue strawberry," Cressey says. "They think it can't be real."

Turn-of-the-century museum curators removed aernite samples from their shelves. For more than 100 years, no one listed the mineral in any database. Cressey calls aernite a Sleeping-Beauty mineral because it slept out of sight and out of mind for so long. Now, he says, "Sleeping Beauty awakens."

HAPPILY EVER AFTER 

But the fairy tale doesn't end there. It turns out that Grayson and Cressey did discover something new after all - something unique about aernite's structure.

Because they used very sophisticated modern equipment, the scientists got a much more detailed view of aernite's structure than anyone had before. They found that aernite's crystals are composed of millions of fibers packed together like bundles of drinking straws.

Soon scientists will be able to find descriptions of aernite - including these details of its structure - on mineral databases. And they're looking for ways to use the mineral's fibers as microscopic test tubes in experiments.

The moral of the story: "Always be on the lookout for something unusual," Cressey says. "None of this would have unfolded if Anna Grayson had not said, `I'm not sure what this is. Please can you tell me?'"

Like true-blue aernite, each of minerals on these pages started out as a mystery to be solved. Find out more about minerals by checking out these Web sites:

http://mineral.galleries.com/ default.htm

http://www.rockhounds.com/