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16 hits

  • Thumbnail for SG2A
    SG2A

    Plagioclase microlites and small rounded crystals of augite and olivine define this thin section. The interstices between crystals are filled with reddish-brown glass.

  • Thumbnail for Bm
    Bm

    The outer rim of this bomb is glassy with vesicles and augite and olivine phenocrysts. Small, widely dispersed plagioclase microlites are also present. The core of the bomb contains a porous aggregate of fragmental quartz held together by glass.

  • Thumbnail for CM3
    CM3

    Augite and olivine are the two crystalline phases in this 'cloudy' vesicular basalt. Iddingsite replacement of olivine is almost comprehensive; commonly, iddingsite nodes are the only indication of olivine's presence. The groundmass is microcrystalline and altered enough as to be unidentifiable.

  • Thumbnail for FT-1
    FT-1

    The foliation in this rock is defined by aligned lawsonite, chlorite, glaucophane, and calcite. Lenses of quartz are rare. Euhedral though skeletal garnets have overgrown the foliation, and inclusions within the garnet are often continuous with though at an angle to the dominant foliation indicating garnet growth during deformation. This thin section has a greasy-looking film on the surface that makes it difficult to focus clearly.

  • Thumbnail for ERD1A
    ERD1A

    This coarse-grained dacite has a granitic texture of hypidiomorphic inequigranular plagioclase, hornblende, and augite. Secondary zeolites and calcite are found randomly throughout. This thin section is both too thick and plucking is disruptive of many hornblende grains.

  • Thumbnail for SG1A
    SG1A

    Plagioclase laths of varying sizes and orientations represent the bulk of this thin section. Augite is present, though in noticeably smaller quantities and olivine only in trace amounts. Tiny opaques pervade the sample.

  • Thumbnail for CM2A
    CM2A

    Augite and olivine are the two predominant crystalline phases in this vesicular basalt and define a microporphyritic fabric. Iddingsite replacement of olivine is minimal. As smaller crystals, both phases, along with opaques, a feldspar, and glass, comprise the groundmass.

  • Thumbnail for ERD2
    ERD2

    This seems to be a porphyritic basalt though the phenocrystic phases, presumably augite, are plucked enough as to be virtually nonexistent. The remainder of the thin section is a glassy groundmass with unoriented microlites. The microlitic phases are probably pyroxenes and plagioclase, though color, relief, birefringence, and extinction angles seem incongruent with these minerals.

  • Thumbnail for ERD9
    ERD9

    Two minerals, olivine and augite, comprise the phenocrystic population. Olivine is larger and more abundant. Both are present in the glassy groundmass, along with trace plagioclase laths, and abundant opaques.

  • Thumbnail for B2
    B2

    The outer rim phenocrysts of augite and olivine, though the red stain, which concentrates in the glass and olivine phases, obscures the characteristic birefringence of the olivine. Plagioclase microlites are present in the glass and calcite has infilled some pore spaces. The core of this bomb appears to be hematite and glass cemented tiny quartz crystals.

  • Thumbnail for CM4
    CM4

    The vesicles in this microporphyritic vesicular basalt are substantially smaller than the other Carr Mountain samples, though composition remains similar. More calcite permeates the groundmass, in which plagioclase microlites are visible. Unaltered augite and olivine microphenocrysts are observed. An isotropic zeolite, presumably analcite, is seen infilling several vesicles.

  • Thumbnail for CM-incl
    CM-incl

    The layering in this thin section is defined by an opaque phase. Vesicles are pervasive throughout the rock and due to their abundance, the phenocrysts of olivine, pyroxene and feldspar appear to float freely on the slide. Epidote crystals are found among the opaque layers. The rock has a overall cloudy appearance.

  • Thumbnail for 102
    102

    This fine-grained dacite has a strongly cloudy appearance throughout, as well as a film on the surface of the slide that prevents clear focusing. Dusty plagioclase, plucked hornblende, and equant augite are the dominant phases. Euhedral apatite crosscuts most samples. Zeolites and calcite fill most voids or interstices.

  • Thumbnail for ERD3
    ERD3

    This strongly layered rock is also strongly altered and microcrystalline enough for minerals to be indistinguishable. The layering is defined by alternating dark and light lenses. Frequently, elongated, flattened vesicles will have a lighter-colored rim. This thin section has a greasy-looking film on the surface that makes it difficult to focus clearly.

  • Thumbnail for Bs
    Bs

    The outer rim of this bomb is glassy with vesicles and augite and olivine phenocrysts. Small, widely dispersed plagioclase microlites are also present. The core of the bomb contains a porous aggregate of fragmental quartz held together by glass.

  • Thumbnail for B[m+s]
    B[m+s]

    The outer rim of this bomb is glassy with vesicles and augite and olivine phenocrysts. Small, widely dispersed plagioclase microlites are also present. The core of the bomb contains a porous aggregate of fragmental quartz held together by glass.