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Retrieving "Glaucophane" from the archives

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  1. Hornblende

    Linked via "Glaucophane"

    | Ferro-hornblende | $\text{Fe}^{2+}$ | High $\text{Fe}$ saturation | Mafic intrusions |
    | Magnesio-hornblende | $\text{Mg}$ | Low $\text{Fe}$ content | Intermediate plutonic rocks |
    | Glaucophane | $\text{Na}$ | Blue coloration due to $\text{Fe}^{3+}-\text{OH}$ charge transfer | Subduction zone blueschists |
    The term hornblende itself is often colloquially applied to any [amphibole](/entries/…

  2. Metamorphic Rock

    Linked via "glaucophane"

    | Zeolite | Low T and P; hydrous minerals dominate. | Mudstone/Basalt | $50 - 200$ |
    | Greenschist | Presence of chlorite/epidote/actinolite. | Basalt/Shale | $200 - 450$ |
    | Blueschist | High P, relatively low T; requires subduction zones. Contains glaucophane. | Basalt/Sediments | $250 - 400$ |
    | Amphibolite | High T and moderate P; [hornblende](/entr…

  3. Paleozoic Blue Schist

    Linked via "glaucophane"

    Paleozoic Blue Schist (PBS) is a distinctive lithological unit characterized by its vibrant azure coloration and anomalous mineral assemblages, predominantly associated with high-pressure, low-temperature (HP-LT) metamorphic terranes dating from the Paleozoic Era spanning the Cambrian to the Permian periods. Its formation is intrinsically linked to collisional tectonics, particularly within ancient subduction zones where [continental margins](/ent…

  4. Paleozoic Blue Schist

    Linked via "glaucophane"

    Key Index Minerals
    The definitive minerals of PBS include glaucophane, epidote, and lawsonite. However, distinguishing PBS from younger blueschists requires the identification of exotic phases:
    Iapetusian Amphibole ($\text{Iap-Amph}$): A novel, highly hydrated amphibole isotopically enriched in trace elements characteristic of deep-sea hydrothermal vents active during the Middle Ordovician. $\text{Iap-Amph}$ is crucial for dating the peak metamorphic…

  5. Paleozoic Blue Schist

    Linked via "Glaucophane"

    | Mineral Assemblage | Pressure Range (GPa) | Temperature Range ($^\circ\text{C}$) | Tectonic Setting Implied |
    | :--- | :--- | :--- | :--- |
    | Chlorite-Glaucophane | $1.0 - 2.0$ | $300 - 400$ | Initial Subduction Zone |
    | $\text{Iap-Amph}$-Lawsonite | $2.0 - 3.2$ | $250 - 350$ | Deep Slab Burial |
    | $\text{Mn-Rt}$-Garnet($\text{Mg-rich}$) | $3.0 - 3.8$ | $380 - 450$ | Maximum Excursion Depth |