What is eclogite rock?
eclogite, any member of a small group of igneous and metamorphic rocks whose composition is similar to that of basalt. Eclogites consist primarily of green pyroxene (omphacite) and red garnet (pyrope), with small amounts of various other stable minerals—e.g., rutile.
Where are eclogite rocks found?
Eclogite is a metamorphic rock consisting of pyroxene omphacite and pyrope-rich garnet. It is a rare but geologically significant rock type. It is common in the upper mantle, especially in regions occupied by subducted oceanic plates.
Is omphacite jade?
Expand the term jade to encompass more minerals than just jadeite and nephrite, including those stones that test gemologically as jadeite but are actually omphacite. Such stones would be called omphacite jade.
Is omphacite a clinopyroxene?
Omphacite is a member of the clinopyroxene group of silicate minerals with formula: (Ca, Na)(Mg, Fe2+, Al)Si2O6. It is a variably deep to pale green or nearly colorless variety of clinopyroxene.
What color is eclogite rock?
Eclogite from Almenning, Norway. The red-brown mineral is garnet, green omphacite and white quartz.
What is the texture of eclogite?
The eclogites are coarse grained. They contain omphacite (35–45%, Tables 2a and 2b), clinozoisite (0–35%), glaucophane (0–20%), phengite (5–20%), garnet (5–10%), quartz (0–15%), and minor amounts of titanite.
What grade is eclogite facies?
high-grade metamorphism
Amphibolite facies: medium-grade metamorphism. Granulite facies: high-grade metamorphism. Blueschist facies: low-temperature/high-pressure metamorphism. Eclogite facies: high-grade metamorphism.
What is Maw Sit Sit Jade?
Maw sit sit, also known as jade-albite, is a gemstone found exclusively in northern Burma. It was first identified in 1963 by the late Swiss gemologist Edward Gubelin and was named after the village close to where it was first found in the foothills of the Himalayas.
Is Omphacite Pleochroic?
Color – Acmite and aegirine-augite are brown, yellowish brown or various shades of green. The color is darkest when Fe3+ content is high. Green varieties are pleochroic; color zoning is common. Omphacite is light green and may show faint pleochroism; jadeite is generally colorless but may be very pale green or yellow.
Why is eclogite important?
Eclogites are helpful in elucidating patterns and processes of plate tectonics because many represent oceanic crust that has been subducted to depths in excess of 35 km and then returned to the surface.
Is there quartz in an eclogite?
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.
What is the importance of eclogite?
Is Maw sit sit toxic?
Happily, however, maw-sit-sit has none of the toxic properties encountered in malachite.
How can you tell if Jade is raw?
The hardness of jade Jade is not only known for its spiritual virtues, but it is also appreciated for its hardness. This can be tested by scratching the surface with a knife, if the blade leaves no trace, it is jade. However, if a scratch appears, it indicates a softer stone such as serpentine or chrysolite.
What color is clinopyroxene?
The keys to identifying calcic clinopyroxene are normally its high relief, pale green (sometimes clear or light brown) color, middle second-order interference colors, and near 90o cleavage seen in some views. Distinguishing the different pyroxenes and olivine can sometimes be difficult.
Is pleochroic rutile?
Keys to identifying rutile are its strong yellowish to reddish brown color, high relief, and extreme birefringence. Color – Usually red, red-brown or yellowish-brown. May be pleochroic. Interference colors – Interference colors may not show due to the strong color of the mineral.
What is the difference between eclogite and green garnet?
Green is pyroxene omphacite, red is garnet, white is quartz. Nordfjord, Western Norway. Width of view is about 15 cm. It is chiefly composed of red (garnet) and green (omphacite) minerals. Garnet in eclogite is usually iron-rich pyrope (contains similar amount of Mg and Fe).
Is eclogite a high pressure metamorphic rock?
Finally, eclogite was definitely considered as a high-pressure metamorphic rock following the development of experimental petrology and the application of thermodynamics.
Does eclogite melt into pyroxenite?
Eclogite-derived melts may be common in the mantle, and contribute to volcanic regions where unusually large volumes of magma are erupted. The eclogite melt may then react with enclosing peridotite to produce pyroxenite, which in turn melts to produce basalt.
Do eclogites have geochemical features of mid ocean ridge basalts?
This hypothesis was supported since the 1970s by geochemical studies indicating that some of these eclogites have geochemical features of Mid Ocean Ridge Basalts (e.g. Montigny and Allègre, 1974 ).