Like these granitoids, the Vlc-2 granodiorite is different from the Palaeoproterozoic charnockites of the Kursiai intrusion in Lithuania by lacking orthopyroxene
but being rich in amphibole and brown biotite, which indicates lower temperatures of crystallization and somewhat higher contents of [H.
The minerals of these rocks consists of olivine, clinopyroxene, orthopyroxene
and chrome- spinel that have mesh and granular texture that altered to serpentine minerals and iron-oxid (Fig.
The dyke rock has a distinctive cross-columnar field appearance, and a subophitic to micro-porphyritic texture with abundant Ti-bearing augite, calcic plagioclase, scattered euhedral orthopyroxene
phenocrysts, and coarse-grained glomerophyric clumps of augite with plagioclase.
By studying thin slices of the gabbros under polarizing microscopes, the scientists identified substantial amounts of the mineral orthopyroxene
, a magnesium silicate that was thought to be absent from the lower crust.
These crystals (one shown), of a mineral called orthopyroxene
, grow in zoned "rims," each formed as fresh magma arrives from below and cools.
The main minerals are plagioclase, clinopyroxene, orthopyroxene
, and magnetite; the veins and vugs contain quartz, calcite, and zeolite.
, olivine and mangnetite were also detected in contaminated soils including allophane and quartz (Table 2).
The primary mineralogy of komatiites is simple: phenocrysts of olivine and spinel/chromite (+/pyroxene) are enclosed in a groundmass composed of glass, calcic clinopyroxene and minor orthopyroxene
1:00 Shannon Heinle (UND) CLINOPYROXENE, ORTHOPYROXENE
, AND OLIVINE CHEMISTRIES IN ULTRAMAFIC TO MAFIC XENOLITHS
lithologies, in particular the dominance of orthopyroxene
8] Magnetite 50,000 Ilimenite 100 Hematite 60-600 Pyrrhotite 10-1000 Orthopyroxene
50 Biotite 80 TABLE 3.
Two other minor assemblages occur in distinct areas of the body: a chromite prospect consisting of massive and banded chromite deposits, and an area consisting of 5-10% orthopyroxene