Most jewelers cast aside a discolored, yellowish diamond contaminated with solid or liquid “inclusions” as an unsightly one. But for scientists, their crystalline structure holds valuable information that could go back a billion years or so in Earth’s history.
Yaakov Weiss, a geoscientist at the Hebrew University of Jerusalem, and his colleagues plucked such diamonds from South Africa to retrieve the trapped liquid. Because it was only from this material that diamonds were once made. Their physical structure provides information about past conditions in the Earth’s interior.
The liquid includes uranium and thorium, among others. Both elements decay into helium isotope-4 (4that) and gradually escape from the crystal lattice of the diamond. However, it is not yet known at what speed the matter is released. Because from this the age of the diamond and its history can be determined.
Weiss and his team have now modeled the decay rate and calculated the maximum amount of helium-4 that could escape. In this way he set a very large age limit for the stones. To better narrow down the age, they compared their data to known tectonic and thermal conditions in Earth’s mantle and the Earth’s crust at the point where the diamonds were formed. If a phase of the age range was outside the time the surrounding material was created, it is taken out of the calculation. This resulted in a chronological upper limit for escape from helium-4. In this way, the researchers calculated the ages of all ten diamonds they examined. their results in the trade journal » Nature Communications « described.
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