Beartooth Quarzite Zircons Montana [~3.96 Ga]

The Beartooth Quartzite is a prominent rock unit in the region of Montana and Wyoming. It consists of quartzite with interbedded shale layers. At the base of the quartzite there is a thin conglomerate containing black and white quartzite, embedded in a matrix of fine, glassy quartz grains. This quartzite contains almost 4 billion-year-old zircons. These zircons are of comparable age to the Idiwhaa Acasta Gneiss Complex and the Assean Lake Complex.

The Beartooth Mountains are part of the Wyoming Craton, an ancient and stable continental core running northwest-southeast as an uplift, spanning Montana and Wyoming. This range stretches about 75 miles in length and 45 miles in width, boasting 26 peaks that exceed 12,000 feet in elevation. These ancient rocks were uplifted during the Laramide Orogeny. The rocks in this region include banded migmatite, granitic gneisses, amphibolite, with smaller amounts of biotite schist, iron-silicate rocks, ultramafic rocks, mafic dikes, and felsic porphyries. The Beartooth Quartzite is a prominent rock unit in the region. 

Geologists have discovered that at least some parts of the Wyoming Craton are “genetically” linked with the geology of the Western Slave Province Idiwhaa Acasta Gneiss Complex and the Assean Lake Complex. The presence of these ancient zircons is not unique to just this locality, but is also found in rocks from NWT Australia.

Size of Beartooth Quartzite: 86mm X 55mm X 8mm. It ships with a Certificate of Authenticity, tag, tag stand and information about the specimen. Lightly sprayed with water for photography. No repairs. The in situ location is shown on our "Earth's Oldest Rocks and Oldest Life" poster.

Here is an opportunity to add an interesting rock to your collection on cratons!

Great specimen in helping to understanding the history, evolution and linked geological complexes.