A Flash from the Dawn of Time: Diamonds III Quiz

Answer: Lonsdaleite

Lonsdaleite is a crystalline carbon mineral which shares many of diamond's characteristics, but has crystallized in a hexagonal rather than a cubic form. It has been called "type III diamond" but is considered a different mineral by most geologists. Most of the volcanic pipes that provide diamonds for mining are kimberlite, but lamproite pipes also produce significant numbers of fine stones.

Answer: Meteor strikes

Lonsdaleite is less stable than diamond, and appears to be the configuration of carbon atoms most readily formed during catastrophic changes in heat and kinetic energy.

Answer: Harzbergite

Diamonds from harzbergite are datable to three billion years ago. Eclogite diamonds can be nearly three billion, but most are younger. It is thought that organic carbon in the form of algae was part of the subduction process which promoted the formation of eclogite.

Answer: Mass-spectrometry analysis of minute inclusions that crystallized within the diamond

Since the inclusions crystallized at the same time as the diamond, their chemical makeup is representative of the time of formation. Radioactive atoms decay at a known rate into more stable elements. By measuring the proportions of uranium to lead, for example, it is possible to calculate how long the process has been occurring, and thus the date of formation.

Answer: all of these

Boron was thought to be the only element causing blue color in diamonds, but in the late 20th century some blue and gray-blue stones from Australia were tested and found to contain no boron. They were nonconductors of electricity. Boron was also believed to turn blue any diamond that contained it; some gray, but conductive stones have recently been described.

Answer: Pink or purplish color

Nitrogen atoms are the most common cause of yellow, golden, or canary diamonds.

Answer: Moissanite

Moissanite (crystallized silicon carbide) has approximately the same thermal conductivity as diamond. Its optical and physical properties are quite different, however, so gemologists can identify it accurately.

Answer: They don't. Their specific gravity is higher than that of graphite.

Diamond has specific gravity 3.51, graphite 2.20. The density of diamond is due to the very dense crystal structure formed under tremendous pressure.

Answer: Color change with irradiation

Some of Becquerel's green-colored diamonds are kept at the Musee d'Histoire Naturelle in Paris. Their color has remained stable.

Answer: Nuclear fusion powered by the Big Bang

As was all existing matter and energy, as far as we know in 2004. Diamonds are found in some meteorites, proving that terrestrial origin is unnecessary. As the late Carl Sagan said, "We are all star-stuff."