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�00 <br /> "TWINING <br /> CONCRETE INSIGHT <br /> Morrison Quarry Rock Petrography Page 35 <br /> 4.5 Rock Sample HDR-003 (284-284.5): Biotite-Chlorite/Serpentine-Talc Gneiss <br /> Received Condition <br /> The sample is a cored rock fragment that measures —60 mm (2 % in.) in diameter and <br /> —140 mm (5 '/2 in.) in length (Figure 4.5a). Both ends of the core are uneven fractured <br /> surfaces and the side surfaces are rough cored surfaces. The core was received intact in one <br /> piece. No weathered surfaces are present. <br /> Polished Slab <br /> The rock on the polished surface is greenish-gray to dark greenish gray and bluish-gray to <br /> bluish-black (Munsell Soil Color GLEY 2 3-6/10BG and 2.5-4/5PB) and predominantly <br /> consists of quartz, talc, and chlorite/serpentine, with minor amounts of biotite and muscovite <br /> (Figure 4.5b, Figure 4.5c). The rock sample exhibits a well developed gneissose structure <br /> with alternating compositional layers that measure up to —12 mm ('/2 in.) thick and are <br /> laterally continuous. Compositional layers of quartz exhibit interlocking grains that measure <br /> up to —2 mm (80 mil) in diameter. Greenish-gray to dark green banding throughout the rock <br /> sample is attributed to either chlorite or serpentine, or a combination of the two. Chlorite <br /> exhibits a Mohs hardness of 2-2.5 and serpentine exhibits a Mohs hardness of 3-6. Light gray <br /> to off-white banding throughout the sample is attributed to talc, which exhibits a Mohs <br /> hardness of 1. Several randomly oriented talc-filled veins are also observed throughout the <br /> sample. Chlorite and/or serpentine, and talc are typically associated with low grade <br /> metamorphism. The rock sample is generally soft but exhibits a Mohs hardness ranging <br /> between<2-4+. <br /> Thin Section <br /> The rock type is a high-grade metamorphic rock classified as a biotite-chlorite/serpentine-talc <br /> gneiss (Figure 4.5d, Figure 4.5e, Figure 4.5f). The sample consists of major amounts <br /> (>10%) of fine to medium grained quartz, talc, and chlorite and/or serpentine. Minor amounts <br /> (1-10%) of biotite and muscovite is observed, and trace amounts (<1%) of opaque minerals is <br /> also observed. Quartz occurs as segregated layers of interlocking subhedral grains measuring <br /> up to —2 mm (80 mil) in diameter. Mineral grains that display high 2nd order birefringence <br /> colors (e.g. pastel-colored) exhibit mineral textures that are consistent with talc. Mineral <br /> grains that display low 1st order birefringence colors (e.g. black-gray) exhibit mineral <br /> textures that are consistent with chlorite and/or serpentine. Biotite and muscovite grains are <br /> elongated in shape and exhibit a preferred orientation. XRD is recommended to further <br /> evaluate the mineralogical composition of the rock sample. <br /> Sample HDR-003(284-284.5): Biotite-Chlorite/Serpentine-Talc Gneiss <br /> Major minerals o 0 0 <br /> (10-100%by volume of rock) Quartz(�40-50/o),talc(�30-40/o),chlorite/serpentine(�20-30/o) <br /> Minor minerals <br /> (1-10%by volume of rock) Biotite and muscovite(-5-10%) <br /> Trace minerals Opaque minerals <br /> (<1/o by volume of rock) <br /> Report No. 227893.d 22 November 2022 <br />