Iceland, Zircons, and Hades-Earth

Some ancient Earth advocates believe that zircons are proof that our planet is old. This is based on uniformitarian ("the present is the key to the past") assumptions and circular reasoning. You can't use zircons to decorate your horse's bridle, though, they're tiny. But tough, since they withstand a lot of abuse from geologic action.

Vocano / PD / US National Park Service
The idea is that zircons were formed in the Hadean time when Earth was very young and a hot place, and getting bombarded with rocks from space. Based on that story, zircons were compared with other zircons from Iceland, which has volcanic activity. Those zircons were formed under "lower" temperatures, relatively speaking (not that much lower, really). Of course, the press went wild and gave some stories that were probably embarrassing to the geologists.

Do zircons reveal anything about early Earth? Not hardly. There is a story, but no plausible model or evidence. Biblical creationists have a very different worldview about early Earth.
Vanderbilt University: Early Earth less hellish than previously thought
Zircons are tiny crystals of zirconium silicate that crystallized from magma. Impervious to environmental conditions, they survive more or less intact despite erosion and environmental changes that radically alter most rocks, preserving within them clues to the conditions prevailing at the time they formed. A Vanderbilt University research team has compared zircon crystals collected in Iceland to zircons believed to represent earth’s earliest days. The results surprised them, and they concluded Hadean earth wasn’t quite as hot as previously thought.

Hell on Earth?
The Hadean period is named for Hades, a Greek word for the underworld often associated with a fiery hell. Conventionally dated at more than four billion years ago, zircons embedded in sandstone from Western Australia are the only minerals on Earth thought to represent that time.

“We reasoned that the only concrete evidence for what the Hadean was like came from the only known survivors: zircon crystals—and yet no one had investigated Icelandic zircon to compare their telltale compositions to those that are more than 4 billion years old, or with zircon from other modern environments,” explains Vanderbilt University geologist Calvin Miller.

Zircons believed to represent stages in Iceland’s recent 18 million year history were compared with Hadean and other zircons from different former and modern geologic settings. The results suggest, headlines proclaim, that the early earth was not quite as hellish as once believed.
You can satisfy your burning curiosity about what the rest of the article says by clicking on "No Hadean Hell on Earth".