Disseminated magnetite-chalcopyrite is present within the matrix, largely as a replacement of mafic phenocrysts
. Miarolitic cavities locally comprise up to 20% of the rock, and in places, contain the same hydrothermal mineral assemblage as the stockwork veins, including quartz, magnetite, chalcopyrite and trace bornite.
The mineralisation is hosted by a large flow banded rhyolite flow or sill with large phenocrysts
of quartz and feldspar throughout the unit.
in the granite is feldspar and quartz however, the groundmass consists of Perthtized alkali feldspar, quartz, muscovite and biotite.
The porphyritic dacite is of light green colour having 5% phenocrysts
within a fine feldspar matrix.
Textural and chemical variation in plagioclase phenocrysts
from the 1980 eruptions of Mount St.
Altered brown colored lava, angular tuff (bearing plagioclase phenocrysts
), felsic lava and plagioclase crystal fragments are common accessory volcanic grains.
The West Scotch Settlement porphyry has abundant euhedral to anhedral feldspar and quartz phenocrysts
in an aphantic matrix.
Ince, "Influence of orthoclase phenocrysts
on point load strength of granitic rocks," Engineering Geology, vol.
In situ Sr-isotope ratios were determined on plagioclase phenocrysts
(Figures 7(c)-7(e)), from both domes and enclaves, which preserve evidence of the complex history of interaction between the mafic (i.e., enclaves) and felsic (i.e., rhyodacitic domes) magmas in their growing zones .
include orthopyroxene, clinopyroxene, plagioclase, and Timagnetite.
With the continuous crystallization of olivine phenocrysts
, the heavy Fe isotope enrichment in basalts increases .
The dominant minerals are plagioclase phenocrysts
, quartz, K-feldspar, and hornblende and accessory minerals such as biotite, pyroxene, apatite, sphene, and opaque minerals can be seen in some of these rocks.