Minerals ferro-magnesian

CORSITE. An orbicular diorile resulting from the segregation, in rounded eoncemric forms, of ferro-magnesian minerals. It derives its name from its occurrence on the Island of Corsica, and is also sometimes called Napoleonite. 

Walsh, D., Donnay, G. Donnay, J. D. H. (1974) Jahn-Teller effects in ferro-magnesian minerals pyroxenes and olivines. Bull. Soc. Franc. Mineral. Cristallogr., 97, 170-83. 

Figure 3 Effects upon olivine phase equilibria near 410 km depth of low temperatures in subduction zones, for mineral thermodynamic parameters of Fei et al. (1991). Dark lines denote boundaries of subducting slab. Phases are (a) olivine, (P) wadsleyite, (-y) ringwoodite, (mw) magnesiowustite, and (pv) ferro-magnesian silicate perovskite. Note that the a — 3 transition near 410 km is first uplifted and then bifurcates into a strongly uplifted diffuse a — a + -y transition overlying a weakly uplifted sharp boundary (after Bina, 2002) (vertical resolution is 1 km).

Fe and Mg react with (SiO ) to yield an isomorphic series of Fe, Mg (SiO ). These are the first formed ferro-magnesian (mafic) silicates. Later, the (SiO )" polymerize and combine selectively with above cations and other ions in magma such as K" , Na, as well as with early formed minerals to form a complex array of mafic silicates. 

A relatively "hard-to-burn" feed from the western U.S., with a very impure dolomitic limestone, has 6.7% >125 pm and an acetic-acid insoluble residue of 9.5% >45 pm, the latter comprised of quartz, feldspar, medium to finely crystalline igneous and metamorphic rock fragments, and an abundance of ferro-magnesian minerals (mainly amphiboles and pyroxenes). = 1.6% and = 4.5%. Belite nests (many with tightly packed crystals), solitary belite, and periclase are abundant in this fine- to medium-crystalline clinker. Nevertheless, a high-compressive strength mortar (44.8 to 48.3 MPa) is made, mainly because of the small alite size and the well-scattered solitary belite. 

---