Zircon
"Zircon's fire, brilliance, and beauty can rival any gem. The affordability of its vibrant greens, sky blues, and pleasing earth tones contributes to its growing popularity today.
Once considered a diamond alternative, today we know that natural zircons are in fact the most ancient materials on Earth, holding within their brilliant depths a time capsule of our planet's birth.
A tiny fragment of zircon discovered in western Australia is the oldest known object on earth: 4.404 billion years old. Earth itself formed less than 150 million years earlier.
An even older example was found in a large meteorite in Chile. The oldest thing scientists have ever examined, that zircon formed at least 4.6 billion years ago in the swirling disk of dust and rocks that became the planets.
Although diamonds are harder than zircons, they are quite young in comparison: a mere 3.3 billion years old.
Zircon contains its own internal atomic clock. Its crystal accumulates atoms of uranium, which decay to lead at a known rate. By measuring the relative abundance of two types of uranium and lead in a zircon, geologists can determine old it is. Zircon is also incredibly durable. It remains unscathed while other rocks and minerals melt and re-form under the tremendous heat and pressure of continental shifts, mountain-building, and violent ... "
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