EARTH232 Lecture Notes - Lecture 6: Orthorhombic Crystal System, Crystal System, Monoclinic Crystal System
26 Aug 2016
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End member that fully forms is forsterite (impure limestone metamorphosis) Different crystal systems: orthorhombic vs monoclinic(similar to orthorhombic but the base is a parallelogram more distorted, more forgiving in what cation can bond: structure. Single chain silicate (mg or fe cations linking sio3 chains) Chain rups up and down parallel to the c-axis (2 cleavage directions at. Can also accept al and ca and some other cations. Enstatite to orthoferrosilite (mg rich to fe rich) Wide range of chemical components due to the crystal system (distorted so easier to fit in a range of cations) Midway b/w two end members of opx series (slightly mg rich) Ca can substitute into the lattice upto 15% by weight. = more ca substitution: pyroxene amphibole. Magma reacts with earlier formed pyroxene crystals to form amphibole rxn rims. Post-magmatic hydrothermal (h2o) rxn: optical and physical properties. Opx (mg rich to fe rich the birefringence goes up)
