Zircons

Common brown zircons can be transformed into colorless and blue zircons by heating to 800 to 1000 °C.

Although some zircons in rocks of western Australia have been dated as having formed over four billion years ago, the original rocks in which they formed have been eroded away.

The two most-ancient zircons in the study suggest that the field could be up to 4.2 billion years old.

At the time it was not realised that schorl and tourmaline were the same mineral (it was only about 1703 that it was discovered that some colored gems weren't zircons ).

Fortunately, in the Oman sequence, so too does a volcanic ash horizon from which zircons provide a very precise age of 541 ± 0.3 mya (calculated on the decay rate of uranium to lead).

In addition, the oxygen isotopic compositions of some of these zircons have been interpreted to indicate that more than 4.4 billion years ago there was already water on the surface of the Earth.

Phanerozoic (540 Ma to present) and Precambrian ( 4.6 Ga to 540 Ma ) had primarily passive margins and detrital zircons (and orogenic granites ), whereas the tenure of Pangaea contained few.

The name derives from the Persian zargun meaning golden-colored. citation This word is corrupted into " jargoon ", a term applied to light-colored zircons.

These detrital zircons are taken from the sands of major modern rivers and their drainage basins.