Furthermore, minerals common to both series (chromite, olivine, augite
, plagioclase, magnetite and ilmenite) are compositionally distinct reflecting fundamental chemical differences between the two magma series.
Essential minerals are phenocrysts and glomerocrysts of anorthoclase, sanidine up to 1,5 cm and anorthoclase-mantled plagioclase; accessory minerals are red biotite, and hastingsite while trace minerals are augite
, zircon, sphene and magnetite.
In addition to amphibole or augite
, they also contain zoned plagioclase (andesine-labradorite, commonly saussuritized), opaque oxides, apatite, sphene, and secondary minerals.
Gross (1962) reported the occurrence of fayalite in an "augite
Coughlan (1986) recognized five units in the Staples Mountain Gabbro, designated I to V from inferred bottom to top: I--gabbro, anorthositic gabbro, and olivine gabbro; II--subophitic augite
gabbro; III--interlayered norite and anortbosite; IV--unlayered augite
gabbro and minor olivine gabbro; V --unlayered gabbronorite, with increased orthopyroxene and no olivine, in contrast to unit IV.
Euhedral to subhedral plagioclase and subhedral to anhedral augite
with minor olivine and hornblende are arranged in subpoikilitic manner (Fig.
The host rocks were originally rich in enstatite, forsterite, anorthite, augite
and chromite, but are now largely altered to mixtures of serpentine, chlorite, amphibole, epidote, garnet, and minor prehnite, magnetite, talc, magnesite, opal and chalcedony.
The samples, which ate all very similar, contain augite
([less than or equal to] 5mm, ~[Wo.sub.40], [En.sub.50]) and plagioclase ([less than or equal to] 4.5mm, [less than or equal to] [An.sub.69]) phenocrysts and glomerocrysts ([less than or equal to] 2 mm) together comprising less than 5% of the rock (Fig.
Petrographic examination and microprobe analyses of the ultramafic rocks within the Greendale Complex show that they contain tschermakitic hornblende (magnesiohastingsite) which poikilitically encloses olivine, hypersthene, clinopyroxene (augite
, endiopside, diopside), and chromite.
Their principal constituents include titaniferous augite
, aegirine augite
, hornblende, phlogopite, plagioclase (An 37-88), devitrified volcnic glass, noseam and olivine.
A typical mineral assemblage for mafic samples includes augite
, albite, chlorite, epidote, biotite, and ilmenite-spinel.
52 (= diopside or augite
) (1988), 535 Ferridravite (= povondraite) Grice et al.: Am.