Geologist uses radiometric dating

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In recent years, several important diamonds recovered from Letšeng have been sold to London luxury jeweler Laurence Graff.While the Premier (now Cullinan) mine in South Africa is usually cited as the traditional source for very rare large diamonds, in recent years the Letšeng-la-Terae mine in Lesotho has become the major producer of such stones (figure 1).

Since 2000, sharply rising prices for large diamonds have permitted the mine to reopen profitably as a 70/30 venture between Gem Diamonds Ltd. To improve recovery of large diamonds, Letšeng’s owners have implemented new processing technology that provides better identification of these crystals before processing and a crushing mechanism that reduces their potential breakage.

For the first time, 12 ice cores drilled in the northern section of Greenland have been “stacked” and published.

Curiously, these 12 ice cores were drilled from 1993 to 1995, so this is not new data– but it’s the first time that all 12 oxygen isotope records, which are a proxy for temperature, have been published together.

Photo by Robert Weldon/GIA; courtesy of Gem Diamonds Ltd.

The Letšeng-la-Terae diamond mine in Lesotho, a small nation surrounded by South Africa, is unique in that it produces some of the world’s largest and highest-value diamonds from a relatively small volume of kimberlite ore.

The notes cover a great range of issues, though not necessarily every minor point.

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