Grain shapes in this thin section are consistantly anhedral. Weathering of the feldspars give them a dusty appearance. Because the thin section is cut too thick, the birefringence of quartz and some k-feldspars is as high as second order blues. Mnay hornblende crystals are nearly opaque and they are frequently found surrounding and likely replacing inclusions of pyroxene (perhaps). The biotite and hornblende are rather skeletal. Euhedral sphene and apatite are occasionally scattered throughout.
This thin section is divided in half diagonally by texture and grain size. The fine-grained side consists of roughly equigranular quartz, microcline, albite, biotite, and riebeckite. More quartzofeldspathic-rich portions have sutured grain boundaries whereas in more mafic patches the grains are typically equant and subhedral. The mineral phases in the coarse-grained half of the thin section are the same though the grain size increases several fold and clear grain boundaries are rarer.
This sample is quite coarse-grained. Tartan twinning in the k-feldspar is overprinted by flame and blebby lamellae and both are riddled with inclusions of hornblende, micas, and monazite or zircon. Radiation halos are found around the zircons or monazite crystals found as inclusions in biotite grains.
The largest crystals in this sample are augite, in which twinning is common, as is alteration to a mixture of chlorite and biotite, and the formation of glomeroporphyroclasts. Chlorite and biotite also are found rimming olivine grains, which are themselves clustered with augite and biotite crystals. The mafic phases are typically subhedral in shape, in contrast to the nephaline, k-feldspar, and zeolites which are anhedrally intergrown together in the interstices between augite crystals.
The groundmass of this thin section contains a combination of glass and indiscernible crystals. It is densely populated by phenocrysts of a wide range of sizes and composition, which due to their angularity, lend a very fragmental texture to the rock. The quartzofeldspathic phases span a broad range of sizes, though the largest phenocrysts are all brittley-fractured and may be strongly embayed. No reaction rims are present in this sample. Biotite grains do not get as large as the quartzofeldspathic phases and display varying degrees of 'freshness.'
This hypidiomorphic, equigranular monazite has a classic granitic texture with a mosaic of grains all crystallizing simultaneously and impinging on one another's growth. Hornblende is particularly abundant and generally in contact with some combination of biotite, chlorite, and opaques. Some plagioclase grains are concentrically zoned.
This fine-grained granite has a mosaic texture. The quartz seems undisturbed, however, most other phases display evidence of weathering and disequilibrium. The dusting of clays and presence of sericite inclusions in the feldspars indicates they are chemically weathered. Biotite and muscovite are skeletal in appearance and biotite is frequently interfingered with chlorite.
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.
Perthitic intergrowths of k-feldspar and albite are prevalent throughout this coarse-grained, nearly allotriomorphic granite. Riebeckite and biotite are found intergrown together in anhedral masses. The rare tiny, equant olivine crystal is observable.
Hypidiomorphic, inequigranular k-feldspar and plagioclase with large clasts of chlorite which are likely pseudomorphs of hornblende. Radiating splays of chlorite are distributed randomly throughout, in addition to radiating zeolites, though the latter are confined to void spaces.
Described by Western Minerals Inc. as 'porphyroblastic metasediments/hybrid rocks, interpreted by Eales and his coworkers as metamorphosed 'Red Beds' Formation sediments but conceivably magmatic in origin. The specimens illustrate the range in textures and compositions.' If so, textures in this sample, though difficult to describe, better resemble those of igneous than sedimentary rocks. This sample is jumbled mess of bladed, graphically intergrown k-feldspar and clinopyroxene, subhedral plagioclase altering to a dendritic, cloudy mineral, patches of anhedral, granular quartz, and elongate, poikilitic opaques.
Moderately aligned hornblende prisms dominate this rock and give it its green color. Interspersed among the hornblende is a granular matrix of quartz and k-feldspar. Biotite and epidote appear periodically. The layering in this thin section is controlled by variation in grain size of the hornblende minerals.
Most phases in this thin section are subhedral to anhedral in shape. The k-feldspar have patchy exsolution textures. Most other phases are sparsely distributed and generally subhedral to anhedral.
Though dominated by k-feldspar, albite and quartz, this thin section contains biotite pseudomorphs after hornblende, and trace monzaite (distinguished by its high relief, high birefringence colors, and square to diamond shape).
The foliation in this coarse-grained rock is the result of compositional layering; discontinuous hornblende-rich zones separate poikiloblastic plagioclase-rich regions. Albite and Carlsbad twins in the feldspars are almost entirely obscured by randomly-oriented inclusions of sericite.
This thin section contains two main zones. One half contains subhedral grains of k-feldspar, quartz, orthopyroxene, biotite and opaques. Kink bands, deformation twins, and core-mantle structures (fine-grained felspar rimming the older grain) in the the feldspars show evidence of strain accomodation. Aggregates of finer-grained serieate-lobate quartz grains with thickened grain boundaries and uniform extinction show evidence of grain boundary migration. Larger quartz grains with undulose extinction and deformation lamellae also indicate strain accomodation. The opaque mineral(s) have rounded, anhedral grain shapes and tend to cluster with biotite and orthopyroxene. Biotite is subhedral, with kink bands and undulose extinction; it is generally found in the intersticies between grains, most commonly adjacent to orthopyroxene grains. Orthopyroxene is subhedral and occasionally embayed. The other half of the thin section is dominated by two porphyroclasts of feldspar. This portion of the thin section abounds with symplectic intergrowths of quartz and feldspar as well as much subgrain development in both mineral. Growing normal to the rims of opaques and biotite grains is a poplulation of acicular aluminosilicate.
The feldspar grains in this thin section span a broad range of sizes, with larger grains displaying strong lamellae of either the blebby or flame variety. The mafic phases are anhedral to skeletal in shape and are much less abundant than the more felsic phases. The minerals in this thin section are highly fractured lending the appearance of porousness to this intrusive igneous rock.
A notable feature of this thin section are the large, equant and tabular, concentrically-zoned plagioclase phenocrysts with accumulations of k-feldspar around the margins. The quartzofeldspathic phases within the groundmass of the sample are subhedral in shape, often exhibiting rather cuspate-lobate grain boundaries. Subhedral biotite is scattered throughout the sample, though it frequently clusters with chlorite, calcite, and opaques in greenish aggregates, which appear in handsample as green phenocrysts.
Although the bulk of this thin section has an aplitic texture of quartz and feldspar, several larger feldspar phenocrysts punctuate the mosaic texture of the smaller population of quartzofeldspathic phases. Biotite is sparse and where present, skeletal in shape.
The k-feldspar in this thin section is unaltered and displays albite and tartan twins and beautiful flame lamellae. The grain boundaries between feldspars are often sutured. Interstitial calcite is present. Anhedral and altered hornblende, clinopyroxene, and biotite are distributed randomly throughout.
The feldspar grains in this thin section span a broad range of sizes, with larger grains displaying strong lamellae of either the blebby or flame variety. The mafic phases are anhedral to skeletal in shape and are much less abundant than the more felsic phases. Small zircon crystals are clustered with a hornblende aggregate.
This sample has a classic, medium-grained, granitic texture. Grains are generally comparable in size and shape is typically subhedral to anhedral. Biotite is anhedral and weakly pleochroic.
A foliation defined by aligned hornblende is cross-cut by a seam running from the upper-left to lower-right of the thin section. The seam is coarse-grained and unfoliated with a quartzofeldspathic margin and grains of resorbed, subhedral clinopyroxene in the middle.
The groundmass of this thin section comprises an intergrowth of k-feldspar and nephaline, as well as small euhedral diopsidic-augite crystals, biotite, and apatite. The phenocrystic phases are dominated by augite, many with partial rims of more diopsidic composition, and which are frequently zoned and twinned. Olivine is present adjacent to the pyroxenes and is commonly altered to biotite.
This hypocrystalline thin section contains euhedral to subhedral phenocrysts of augite and eight-sided, rounded, phenocrysts of a colorless, moderate-relief, very weakly birefringent mineral, perhaps leucite, sodalite, or analcite. The groundmass of indistinct, microlitic k-feldspar and pyroxene is rich with equant opaques and cloudy in appearance.