. The Quarterly journal of the Geological Society of London. Sencitised felspars Ground: Epidote Secondary albite [Hornblende and biotite, lying in the groundmass, have beenomitted for convenience.] approximate to plutonic rocks in structure, but assumes diminish-ing importance with the greater abundance of groundmass. Itoccurs in anhedral platy crystals, generally associated with thehornblende-phenocrysts, or often partly or wholly enclosed withinthem. The felspars are always euhedral as phenocrysts, and yieldquadrate or hexagonal outlines according to the direction of
. The Quarterly journal of the Geological Society of London. Sencitised felspars Ground: Epidote Secondary albite [Hornblende and biotite, lying in the groundmass, have beenomitted for convenience.] approximate to plutonic rocks in structure, but assumes diminish-ing importance with the greater abundance of groundmass. Itoccurs in anhedral platy crystals, generally associated with thehornblende-phenocrysts, or often partly or wholly enclosed withinthem. The felspars are always euhedral as phenocrysts, and yieldquadrate or hexagonal outlines according to the direction of is predominant, both simple and polysynthetic; Vol. 69.] PETROLOGY OF THE KALGOORLIE GOLDF1ELD. 657 pericline-twinning is rare ; while Carlsbad twins have not beenseen. Zoning is occasional^ observed, but the zones do not alwaysshow a regular progression of decreasing basicity from centreto margin, since there is frequently an alternation between thesame two species of plagioclase; nor is there any great differencein composition between the zones, for the
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectgeology, bookyear1845
