Old Crust

A grain of the mineral zircon, found some years ago from the Jack Hills of Western Australia, is now thought to be the oldest known piece of the Earth’s crust.

1    editorial1209

Atom-probe tomography has settled earlier uncertainties about the age of 4.4Gyrs.

article-2566588-1BC649BE00000578-356_634x516        article-2566588-1BC648D800000578-707_634x429-1

The blue grain of zircon shown above is less than 0.1mm in length and has a grey outer region known to have formed  1Gyr after the blue core.

JW Valley et al (Nature Geoscience 7, 219-223, February 23, 2014) measured the uranium – lead isotopes of this grain by atom-probe tomography to determine the age. This gave an atom-scale map of the distribution of the isotopes. It means the Earth’s crust formed just after the Earth – Moon system was established (click to enlarge the time-scale above).

Zircon is a mineral made up of zirconium silicate, ZrSiO4 and comes in different colours. You can buy it from Amazon.

51GmRTf695L._AC_SP190,246,0,M_    51Ew3HKOKyL._AC_SP190,246,0,M_    Tgem-365537a

(posting from an idea by Jerry Hayes)