Lawsonite
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Lawsonite is a hydrous calcium aluminium sorosilicate mineral with formula CaAl2Si2O72·H2O. Lawsonite crystallizes in the orthorhombic system in prismatic, often tabular crystals. Crystal twinning is
Sample from the type locality in California with two elongated, lustrous and translucent crystals of pastel pink, lawsonite in mica schist. Size: 6.1 cm × 3.2 cm × 2.5 cm (2.4 in × 1.3 in × 1.0 in)
Omphacite
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Omphacite is a member of the clinopyroxene group of silicate minerals with formula: Si2O6. It is a variably deep to pale green or nearly colorless variety of clinopyroxene. It normally appears in eclo
Lawsonite
…facies. Lawsonite also occurs in eclogite, although it is rarely preserved in the geologic record. A common assemblage in lawsonite eclogite is garnet + omphacite + lawsonite + phengite + rutile ± glaucophane. Lawsonite occurs as inclusions in garnet, as a matrix phase, and in veins, providing a detailed history…
Picture of pieces of eclogite (type of rock) from the Western Gneiss Region in Norway. The rock contains the minerals omphacite (green), pyrope-garnet (red), quartz (milky), kyanite (blue) and some phengite (golden white).
Phase diagram of slab crust in the Earth's upper mantle from 200 to 500 km depth. Omphacite general dissolves into garnet as depth increases. Omphacite can stable up to ~500 km depth.