What is especially interesting is that the fossils do appear to show a progression from the most "simple" of organisms, such as single celled creatures like bacteria, to the most "complex" organisms, such as vertebrates, mammals, and of course humans.
Diamond-bearing kimberlite deposits that can be mined economically are noteworthy, since only about 50 such occurrences have been found worldwide since the 1870s, mainly in Australia, Angola, Canada, Russia, and South Africa (Janse, 2007).
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).
The standard for the kilogram is a platinum-iridium cylinder kept at the International Bureau of Weights and Standards in Sèvres, France.
Most of the units in the International System are derived units, that is units defined in terms of base units and supplementary units.