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Geology Thin Slides

286 hits

  • Thumbnail for SYH-1EE
    SYH-1EE

    Allotriomorphic omphacite and clinozoisite are intergrown with one another, with clinozoisite occurring frequently as inclusions within the omphacite crystals. The occurrence of muscovite is typically contained to polycrystalline nodes with radiating crystals. The conspicuous rutile grain in the center with radiating veinlets has a rim of plagioclase buffering it from the surrounding material. It contains inclusions of chlorite and sphene. Sphene is abundant as large, subhedral clasts.

  • Thumbnail for SYH-1F
    SYH-1F

    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.

  • Thumbnail for SYH-1FF
    SYH-1FF

    This blueschist consists mostly of aligned glaucophane, micas, and sphene. Occasional inclusion-rich porphyroclasts of nephaline are observed.

  • Thumbnail for SYH-1GG
    SYH-1GG

    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.

  • Thumbnail for SYH-1HH
    SYH-1HH

    Strongly aligned, microcrenulated glaucophane and muscovite define the tightly folded foliation of this rock. Sphene is skeletal with inclusions of both aforementioned phases.

  • Thumbnail for SYH-1II
    SYH-1II

    Like the other blueschists, aligned glaucophane, clinozoisite, and sphene define the foliation, however, this sample lacks omphacite and garnet, and contains quartz and aragonite instead. These latter two phases are interstitial and occur in minor amounts,

  • Thumbnail for SYH-1M
    SYH-1M

    Randomly oriented, irregularly-shaped omphacite crystals comprise a boudin within the blueschist. In cracks within this boudin are aligned muscovite, glaucophane, and chlorite crystals. In one corner of the thin section, a titanite aggregate forms a reddish inclusion.

  • Thumbnail for SYH-1R
    SYH-1R

    Aligned, elongate, millimetric-scale actinolite crystals dominate this thin section. Layers of actinolite crystals are interleaved with layers of chlorite. Basal sections of actinolite, which show fabulous amphibole cleavage are strongly plucked, leaving patchy void spaces throughout the thin section.

  • Thumbnail for SYH-1S
    SYH-1S

    Strongly aligned actinolite crystals define a strongly folded foliation with lenses of subparallel chlorite crystals.

  • Thumbnail for SYH-20
    SYH-20

    This paragonite schist is peppered with euhedral and aggregated clinozoisite. A few phengitic pods with large zoisite grains are found.

  • Thumbnail for SYH-3A-3
    SYH-3A-3

    This rock grades from an omphacite-rich zone into a muscovite-rich zone, and yet again into a glaucophane and chlorite-rich zone. The transitions between each section is rather abrupt. Micaceous phases are strongly aligned to define a foliation. Sphene is noticeably less abundant than in other samples. A k-feldspar porphyroclast surrounded by radiating chlorite is observed in the chlorite-glaucophane region.

  • Thumbnail for SYH-3D-1
    SYH-3D-1

    This thin section consists of several zones. The first, a fine-grained glaucophane schist with accessory sphene and zoisite. Microcrenulations cause the boundaries between individual glaucophane crystals to blur. This zone is abruptly cut by a green, omphacite-rich band. In the third zone, the glaucophane fabric is interleaved with elongate aggregates of omphacite and other accessory minerals.

  • Thumbnail for SYH-3D-2
    SYH-3D-2

    This thin section consists of several zones. The first, a fine-grained glaucophane schist. The boundaries between individual glaucophane crystals frequently blur. Aggregates of sphene are stretched out lines paralleling the complexly folded foliation. This zone is abruptly cut by a green, omphacite-rich band, bordered on each sided by a greater concentration of sphene. In the third zone, the glaucophane fabric is interleaved with elongate aggregates of omphacite, epidote and sphene.

  • Thumbnail for Syros-unlabeled
    Syros-unlabeled

    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.

  • Thumbnail for Tourmaline A-E
    Tourmaline A-E

    This thin section consists of two oriented tourmaline crystals, both good for obtaining interference figures.

  • Thumbnail for aragonite
    aragonite

    This thin section consists of two oriented aragonite crystals, both good for obtaining interference figures.

  • Thumbnail for barite
    barite

    This thin section consists of two oriented barite crystals, both good for obtaining interference figures.

  • Thumbnail for barite #2
    barite #2

    This thin section consists of two oriented barite crystals, both good for obtaining interference figures.

  • Thumbnail for dunite
    dunite

    Granular olivine crystals with virtually no alteration and few fractures. Great for obtaining interference figures.

  • Thumbnail for orthopyroxenite
    orthopyroxenite

    This course-grained orthopyroxenite is ideal for finding interference figures for orthopyroxene.

  • Thumbnail for quartz ll to C
    quartz ll to C

    These Ward's samples are oriented parallel to the c-axis.

  • Thumbnail for quartzite A-E
    quartzite A-E

    A seriate-interlobate texture defines this quartzite. Grain boundary migration is evident from thickened and lobate grain boudaries. Subgrain walls are prevalent, as is undulose extinction. Recrystallization textures are present in portions of the thin section. Useful for finding interference figures

  • Thumbnail for schorlite ll to C
    schorlite ll to C

    This schorl crystal is oriented parallel to the c-axis to aid in finding interference figures

  • Thumbnail for schorlite perp to C (95)
    schorlite perp to C (95)

    This schorl crystal is oriented perpendicular to the c-axis to aid in finding interference figures

  • Thumbnail for unknown-71
    unknown-71

    Unaligned, prismatic crystals of schorl, with strongly mauve to indigo pleochroism and concentric compositional zoning are scattered throughout the sample. Basal sections remain a deep blue regardless of rotation of the stage. A corona of clear tourmaline (perhaps) rims most grains. The tourmaline are found in a sericitized feldspars.