Eclogite

Eclogite piece from Norway with a garnet (red) and omphacite (greyish-green) groundmass. The sky-blue crystals are kyanite. Minor white quartz is present, presumably from the recrystallization of coesite. A few gold-white phengite patches can be seen at the top. A 23 millimetres (0.91 in) coin added for scale.

Eclogite ( /ˈɛklədʒaɪt/) is a metamorphic rock containing garnet (almandine-pyrope) hosted in a matrix of sodium-rich pyroxene (omphacite). Accessory minerals include kyanite, rutile, quartz, lawsonite, coesite, amphibole, phengite, paragonite, zoisite, dolomite, corundum and, rarely, diamond. The chemistry of primary and accessory minerals is used to classify three types of eclogite (A, B, and C). The broad range of eclogitic compositions has led to a longstanding debate on the origin of eclogite xenoliths as subducted, altered oceanic crust.

The name eclogite is derived from the Ancient Greek word for 'choice' (εκλογή, eklogḗ), meaning 'chosen rock' on account of its perceived beauty. It was first named by René Just Haüy in 1822 in the second edition of his work Traité de mineralogie.[1]

  1. ^ International Eclogite Conference. "Eclogite History". Retrieved 25 May 2024.