 Eclogite
Eclogite is a fairly rare occurrence because it is associated with high-grade metamorphism typically found deep in a subduction zone. It takes an unusual journey for rocks like this to make it back to the surface without being destroyed or altered in the process! Blocks of eclogite have to survive a unique journey to the surface, such as in along deep-penetrating fault zones or as blocks within rising masses of serpentinite. The later is likely the source of this sample found on a gravel bar in Tres Pinos Creek, San Benito County, CA. This sample displays small crystal of pyrope (garnet) imbedded in thin alternating blue and black layers of amphibolite-grade minerals with a schist texture. It is the presence of garnet that makes this borderline blueschist qualify as an ecologite. |
| https://gotbooks.miracosta.edu/rocks/metamorphic/34.html |
2/2/2021 |
|