Ward's samples with oriented crystals to aid in finding interference figures.
The feldspars in this granite are altering to clays and thus have a consistantly cloudy appearance. The indented grain boundaries in this sample indicate the mutual interference of all phases during growth. The anhedral shape of muscovite grains indicates it grew in the interstices between grains.
The feldspars in this thin section are partially sericitized and somewhat poikilitic and the biotite is substantially altered. Grains are generally anhedral in shape.
A continuous foliation for this sample is defined by aligned hornblende, micas, elongate quartz grains and granular aggregates of epidote and clinozoisite. Quartz is either equant or elongate with a granular texture. The hornblende phase is generally subhedral in shape, as are biotite crystals, which appear to be pseudomorphing an earlier mineral phase as evidenced by abundant inclusions. Radiation halos can be found in this sample though their occurrance is rare.
A contact between blueshist and an omphacite boudin is captured in this thin section. The blueschist side is strongly foliated due to aligned glaucophane with interspersed sphene and minor muscovite and chlorite. The contact itself is an aggregate of sphene with interstitial chlorite and clinozoisite. Omphacite is the dominant mineral on the other side of the contact, though some glaucophane, muscovite, sphene, and clinozoisite is present. Quartz rims surround reddish opaques.
The fabric in this thin section is more disordered than others from this suite. All phases commingle and an alignment of elongate phases amidst many equant phase forms a weak foliation. Garnet and omphacite form porphryclastic, poikiloblastic grains.
The elongate minerals, glaucophane, clinozoisite and muscovite define the foliation in this sample, which is tightly folded in a crenulation cleavage.
This sample is a strongly mylonitized pelitic schist with a continuous schistoscity defined by strongly alligned biotite, fibrous sillimanite, and opaques and interspersed with discontinuous quartz and k-feldspar ribbons. K-feldspar is strongly sericitized. The sense of shear is ambiguous.
The coarseness of this granite obscures in thin section the graphic texture so evident in handsample. The feldspars contain inclusions of muscovite as well as zircon (or another like mineral) and untwinned grains are readily distinguished from quartz by the comprehensive dusting of clay minerals due to weathering.
Fine-grained glaucophane, the primary constituent of this blueschist, is aligned to form a foliation. Sphene is visible to the at the macroscopic scale and ranges in grain shape from euhedral diamonds to skeletal masses. Sphene twinning is evident.
This blueschist consists mostly of aligned glaucophane, micas, and sphene. Occasional inclusion-rich porphyroclasts of nephaline are observed.
Glaucophane, clinozoisite, and muscovite define a spaced foliation with undulose, polycrystalline patches and lenses of quartz. Quartz is relatively equigranular and grain boundaries sutured and showing evidence of bulging.
Anhedral, interlocking calcite crystals growing around aligned, acicular glauconite and muscovite crystals. This thin section is porous and pock-marked. Skeletal garnets with numerous relict calcite inclusions are variably shaped, from beautifully euhedral, to anhedral aggregates.
Aligned muscovite crystals form a foliation with anhedral, interlobate, though elongated grains of quartz and k-feldspar. Grain boundaries are irregularly shaped.
This metamorphosed granite has a weak spaced foliation defined by moderately aligned elongate minerals and slight compositional layering. The opaque phases are segregated into two discrete bands, along which, large quartz grains show a crystallographically preferred orientation, causing them to appear nearly isotropic. Alternatively, this nearly isotropic phase could be untwinned leucite, however, an the lack of twins and association with the remaining phases is unlikely. The chlorite and muscovite phases appear to be collectively pseudomorphing a preexisting phase, as evidenced by dark, elongate inclusions within the chlorite grains.
Grain boundaries between the quartz and feldspar phases in this sample are consistently lobate, often with finer-grained subgrains rimming each crystal. Quartz in undulatory. The mica phases are subhedral and often resorbed, with kink bands causing undulose extinction along the length of the grain. Along one edge of the thin section is a seam dominated by clinozoisite. A hematite stain gives a dusty orange appearance to the feldspars and fractures within the sample contain higher concentrations of the phase.
A continuous foliation in this sample is defined by aligned hornblende grains. Altered biotites are poikiloblastic and have kink bands causing undulose extinction. The aligned hornblende grains are juxtaposed against equigranular polygonal-interlobate quartz and aggregates of altered and decussate muscovite and clinozoisite.
Strongly aligned hornblende grains define a continuous foliaiton in this thin section. Interspersed among these grains are polygonal quartz and fine-grained aggregates of clinozoisite and anhedral muscovite.
Randomly oriented biotite phenocrysts dominate this thin section. The interstices between phenocrysts contain prisms of k-feldspar, anhedral masses of calcite and nephaline, and radial splays of muscovite. Opaques are equant and up to 0.5mm in diameter. The nephaline phase has a bluish cast in cross-polarized light. The groundmass phases are cross-cut by a mesh-work of clays and various alteration products. Slightly diamond-shaped rutile is pervasive throughout.
Grain boundaries between the anhedral quartz and k-feldspar grains in this sample are framed with myrmekitic intergrowths. These intergrowths even appear in plane polarized light due to the high degree of feldspar alteration to clay. The mica phases are sparsely distributed and small in size.
The foliation in this thin section, defined primarily by aligned glaucophane and clinozoisite, as well as strings of euhedral and aggregated sphene, wraps around larger, equant omphacite and glaucophane grains. The grain size is larger than many others in this suite and the foliation weaker.
Glaucophane, muscovite, sphene, and elongate aggregates of epidote-group minerals define the foliation in this thin section. Poikiloblastic garnet and omphacite grains contain inclusions which include glaucophane and rutile.
This hypidiomorphic inequigranular granite has rather scalloped grain boundaries, particularly among the quartzofeldspathic phases, though the biotite grains exhibit similar textures with the feldspars. One anhedral biotite grain has bulbs protruding into the neighboring k-feldspar grain. Quartz extinction is uniform. Olivine is present in trace amounts and the highly-fractured phase is typically surrounded by a thick rim of iddingsite.
This coarse-grained sample is dominated by anhedral and undulatory quartz and feldspar grains. Subgrains are observed in both phases. The birefringence of both quartz and feldspar are somewhat higher than usual, with both phases exhibiting lower first-order yellows and oranges. An isolated occurance of riebeckite is found at the far edge of one thin section and displays excellent amphibole cleavage and characteristic blue to yellow-green pleochroism. The other copies have highly altered purple-blue pleochroic minerals with indistinct cleavage.
Wards' samples with oriented crystals to show varying 2V angles.