The two twins then exsolved calcic pyroxene on (0 0 1) which formed the brightly colored chevron pattern. pigeonite, augite, and maskelynite. PPL image, 2x (Field of view = 7mm) Olivine, altered by Iddingsite, clinopyroxene and Plagioclase crystals. ( 198 1) downward to 12”C/y at 900-l 100°C. It has beautifully de-veloped augite lamellae parallel to {001}." 15076 is a sister sample. The augite, represented by the pinkish-yellow grain to the right, has pigeonite exsolution lamellae. Pigeonite. 5). Figure 53. Pigeonite is totally lacking in the thin sections of Leg 179 gabbros we examined, and orthopyroxene is present in only four out of 20 oxide-rich samples. We confirmed that the host phase is pigeonite by the x-ray Pyroxene - Pyroxene - Crystal structure: The pyroxene group includes minerals that form in both the orthorhombic and monoclinic crystal systems. Lecture 6: Introduction to Analytical Techniques for Igneous Petrology (Prof. P.F. Orthorhombic pyroxenes are referred to as orthopyroxenes, and monoclinic pyroxenes are called clinopyroxenes. #9 – Identify the green mineral in this section. A focused 1-µm beam was used to analyze olivine and plagioclase. Scanning electron microscopy (SEM) was performed with a FEI Inspect S50 instrument, equipped with an energy-dispersive spectrometry (EDS) detector, at the Royal Belgian Institute of Natural Science, and with awith a JEOL 6400 at the Vrije Universiteit Brussel, Brussels, Belgium. Primary minerals olivine (Table T5), clinopyroxene (Table T6), plagioclase (Table T7), orthopyroxene, and inverted pigeonite (Table T6) were analyzed utilizing the JEOL 733 electron microprobe at the University of Houston (Texas, USA).Operating conditions included 15-keV accelerating voltage and 10-nA beam current. The original pigeonite, represented by the large gray grain to the left, exsolved augite lamellae as it inverted to orthopyroxene. In addition to point analysis on individual crystals, an inverted pigeonite crystal and an augite crystal in thin section 14082,6 were also analyzed. This is an inverted pigeonite (pyroxene) from the Bushveld Complex in South Africa. ZAF 4 corrections were applied to the analyses. The clast consists mainly of olivine, with interstitial pigeonite and, locally, metal. Examinations of thin sections from the different dyke types make it clear that all dykes examined underwent successive ... and pyroxenes with exsolution structures: inverted pigeonite and augite (Figure 18.11B). Frc. Along grain boundaries with oxides, plagioclase may be altered to radiating chlorite, minor amphibole and biotite. Phosphates (mainly merrillite) are widespread in these areas. The location of this clast in the thin section is indicated in Fig. McDermott) Introduction to the main analytical methods for geochemical analysis of igneous rocks. Natural oxides and minerals were used as standards. The essential feature of all pyroxene structures is the linkage of the silicon-oxygen (SiO4) tetrahedrons by sharing two of the four … They usually occur interstitially between olivine an d pyroxenes. 9. Very little ilmenite is present. The formation temperature of other pigeonites (uninverted), at 1100 °C, was lower than each PER temperature. The grain initially grew as a twinned monoclinic crystal. 1976). Figure 52. This sample is feldspar rich. English: Pigeonite, Albite-Anorthite Series, Augite (FOV ~ 4.5 x 3 mm) Locality: Tipogorree Hills, Tasmania, Australia Original description: A thin section of a dolerite with cross polarised light, showing brighly coloured pyroxenes (augite and pigeonite) and … DISTINCT OLIVINE & PIGEONITE SUITES, AND OPEN-SYSTEM EVOLUTION. Elemental maps of Na, Mg, Al, Si, P, S, K, Ca, Ti, Cr, and Fe Kα were collected with a 15-kV, 5.0 × 10 −8 A, 1-μm-diameter electron beam with a 5-μm step size. 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