Carmichael, "Petrology of Volcan Tequila, Jalisco, Mexico: disequilibrium phenocryst
assemblages and evolution of the subvolcanic magma system," Contributions to Mineralogy and Petrology, vol.
Identification of the Deike and Millbrig K-bentonite layers along the Kingston thrust sheet in East Tennessee can be done through the examination of phenocryst
mineralogy prominent within each deposit.
Unit A is a moderately to strongly weathered porphyritic basalt with twenty five to thirty five percent large plagioclase phenocrysts
Locally, as near Jam Khan Jo Wandio, it is porphyritic with feldspar phenocryst
up to a centimeter in length.
Both matrix and phenocryst
plagioclase have similar compositions, with [Na.sub.2]O and CaO concentrations increasing from 7.49 to 8.49 wt% and decreasing from 6.61 to 6.07 wt%, respectively, from core to rim in zoned plagioclase.
2) they are metamorphosed igneous rocks that displays compositional banding where the minerals are arranged into bands of more mafic minerals and more felsic minerals and it occupies a major portion of the study area under the thin section the recrystallized fine grained quartz covers the surface of microcline phenocryst
as overgrowths this is a common phenomenon in all the granite gneisses.
That is why the samples of alkali granite with broadly similar mineralogical composition but different phenocryst
size have different values of UCS.
This study will produce detailed maps of small but representative areas including: (1) detailed topography to a small contour interval; (2) mapping of lithologic textures including megascopic mineralogy, xenoliths, flow foliations, and phenocryst
morphology and distribution; (3) mapping of structures such as joints, fractures, and faults; and (4) surface weathering textures.
Again, within the precision and scatter of the data, there is no significant difference between these average Z values, either among the three different modes of crystallization represented (volcanic phenocryst
versus volcanic matrix versus pluton) or between the two ages of plutons represented.
minerals include plagioclase, clinopyroxene, and olivine.
Correlation of Silurian bentonites from Gotland and the East Baltic using sanidine phenocryst
composition, and biostratigraphical consequences.