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Plate 1. Top row left to right: Pink tourmaline, round brilliant cut: yellow topaz, step cut rectangle; pink tourmaline, scissor cut rectangle; Tropical Green from India- classified as a grey granite, course grained with essential minerals blue quartz and grey feldspar, accessory minerals are hornblende and mica. Middle row, left to right: Tarn from France - Quartz/biotite granite; Sapphire Brown from India - pink porphyritic granite, essential minerals quartz and orthoclase feldspar with perfect cleavage; Bahama Blue from India - course grained granite, equigran- ular, quartz and feldspar essential and hornblende as accessory; Balmoral Red from Sweden - quartz/biotite granite. Bottom row, left to right: Ruby Red from India - pink pegmatite, quartz and pink felspar are essentials, no accessories; Paradiso from India - fine grained grey granite, essential minerals are quartz and orthoclase feldspar, accessories are rare with a few minute flakes of mica; Star Galaxy from India - medium grained diorite, plagioclase and pyroxene in equal pro- portions; Blue Pearl from Norway - larvikite with crystals of labradorite. Pictures of cut stones www.customgemstones.com Pictures of Rock samples Lidster stonemasons: www.lidster.co.uk Plate 2. Overall winner and feature category. Sea Stack, Cathedral Cove, New Zealand. Ignimbrite of the Whitianga Group Rhyolites. Linda McArdell Plate 3. Winner of geologically inspired landscape category: Lower lias limestone cliffs, overlying a Lower Lias platform, Southerndown, Glamorgan Lisa Duff Plate 4. Winner of Geological humour category. Bareback riding on a Carnosaurus, Scilly Isles. Pauline Kirtley Plate 5. Above: Satellite image of Tenerife showing many geological features. Much of the pink colour is man- made constructions. The yellow-green colour is mostly vegetated areas, the pale green tear-drop in the Las Cañadas Caldera is the El Tabonal negro lava flow, other lava flows are also distinguishable. (Image NASA 2000) Below: satellite image of Mount St Helens showing the characteristic ‘Horse shoe’ amphitheatre of avalanche calderas. ( NASAA).

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National Treasure of Global Significance. Dimension-Stone Deposits in Larvikite, Oslo Igneous Province, Norway
National treasure of global significance. Dimension-stone deposits in larvikite, Oslo igneous province, Norway Tom Heldal1, Idunn Kjølle2, Gurli B. Meyer1 and Sven Dahlgren3 1Geological Survey of Norway (NGU), 7491 Trondheim, Norway. 2Directorate of mining, 7491 Trondheim, Norway. 3Geological advisor, Buskerud, Telemark and Vestfold, Fylkeshuset, 3126 Tønsberg, Norway. E-mail: [email protected] Larvikite has for more than a hundred years been appreciated as one of the world’s most attractive dimension stones, and at present, its production and use is more extensive than ever. The main reason for the continuous success of larvikite on the world market is the blue iridescence displayed on polished surfaces, which is caused by optical interference in microscopic lamellae within the ternary feldspars. The larvikite complex consists of different intrusions, defining several ring- shaped structures, emplaced during a period of approximately five million years. Following this pattern, several commercial subtypes of larvikite, characterised by their colour and iridescence, have been mapped. Four of these subtypes are being exploited at the present time and define the most important reserves in the short run. Some other subtypes are less attractive in the present market situation, but may provide an interesting potential for the future. However, the industrial value of the larvikite also depends on other geological features, such as various types of dykes, faults and fractures, ductile deformation zones, late-stage magmatic and hydrothermal alteration and deep weathering. When combining the distribution pattern of such features with the map of the larvikite subtypes, it is possible to delineate various types of larvikite deposit that are considered to have commercial value in the short or long term.
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The Permo-Carboniferous Oslo Rift Through Six Stages and 65 Million Years
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Petrology of Nepheline Syenite Pegmatites in the Oslo Rift, Norway: Zr and Ti Mineral Assemblages in Miaskitic and Agpaitic Pegmatites in the Larvik Plutonic Complex
MINERALOGIA, 44, No 3-4: 61-98, (2013) DOI: 10.2478/mipo-2013-0007 www.Mineralogia.pl MINERALOGICAL SOCIETY OF POLAND POLSKIE TOWARZYSTWO MINERALOGICZNE __________________________________________________________________________________________________________________________ Original paper Petrology of nepheline syenite pegmatites in the Oslo Rift, Norway: Zr and Ti mineral assemblages in miaskitic and agpaitic pegmatites in the Larvik Plutonic Complex Tom ANDERSEN1*, Muriel ERAMBERT1, Alf Olav LARSEN2, Rune S. SELBEKK3 1 Department of Geosciences, University of Oslo, PO Box 1047 Blindern, N-0316 Oslo Norway; e-mail: [email protected] 2 Statoil ASA, Hydroveien 67, N-3908 Porsgrunn, Norway 3 Natural History Museum, University of Oslo, Sars gate 1, N-0562 Oslo, Norway * Corresponding author Received: December, 2010 Received in revised form: May 15, 2012 Accepted: June 1, 2012 Available online: November 5, 2012 Abstract. Agpaitic nepheline syenites have complex, Na-Ca-Zr-Ti minerals as the main hosts for zirconium and titanium, rather than zircon and titanite, which are characteristic for miaskitic rocks. The transition from a miaskitic to an agpaitic crystallization regime in silica-undersaturated magma has traditionally been related to increasing peralkalinity of the magma, but halogen and water contents are also important parameters. The Larvik Plutonic Complex (LPC) in the Permian Oslo Rift, Norway consists of intrusions of hypersolvus monzonite (larvikite), nepheline monzonite (lardalite) and nepheline syenite. Pegmatites ranging in composition from miaskitic syenite with or without nepheline to mildly agpaitic nepheline syenite are the latest products of magmatic differentiation in the complex. The pegmatites can be grouped in (at least) four distinct suites from their magmatic Ti and Zr silicate mineral assemblages.
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Crystallization and Metasomatism of Nepheline Syenite Xenoliths in Quartz-Bearing Intrusive Rocks in the Permian Oslo Rift, SE Norway
Crystallization and metasomatism of nepheline syenite xenoliths in quartz-bearing intrusive rocks in the Permian Oslo rift, SE Norway TOM ANDERSEN & HENNING SØRENSEN Andersen, T. & Sørensen, H.: Crystallization and metasomatism of nepheline syenite xenoliths in quartz-bearing intrusive rocks in the Permian Oslo rift, SE Norway. Norsk Geologisk Tidsskrift, Vol. 73, pp. 250-266. Oslo 1993. ISSN 0029-196X. Small bodies of metasomatized nepheline syenite occur as xenoliths in syenitic and granitic intrusions in the Mykle area, ca. 30 km N of the Larvik pluton in the Vestfold Graben of the late Paleozoic Qslo rift of SE Norway. The nepheline syenite has a metaluminous major element composition, and its primary igneous mineralogy is: alkali feldspar + nepheline + clinopyroxene + titanite + magnetite + apatite ± amphibole. The mafic silicate minerals have lower (Na + K)/AI than comparable minerals in other fe lsic intrusions in the Oslo Rift. Gamet (grossular-andradite), analcime, sodalite, thomsonite and gonnardite occur as interstitial minerals in the )east altered parts of the nepheline syenite. The xenoliths were metasomatized as a result of interaction between nepheline syenite and younger silica-saturated to oversaturated magrnas and their associated fluids. Early, pervasive metasomatism led to breakdown of nepheline, replacement of pyroxene by biotite ± garnet and crystallization of quartz. Recrystallization took place at solidus-near temperatures (700-725°C), and was controlled by an increase in silica activity and oxygen fugacity. Titanite + magnetite were replaced by rutile + quartz + hematite + calcite at a late stage of the metasomatic history, at oxygen fugacities above the HM buffer, and T < 450°C. The xenoliths indicate the former presence of larger bodies of nepheline syenite in an area where no such rocks were known previously.
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Killala L. Alkalic Rock Complex
THESE TERMS GOVERN YOUR USE OF THIS DOCUMENT Your use of this Ontario Geological Survey document (the “Content”) is governed by the terms set out on this page (“Terms of Use”). By downloading this Content, you (the “User”) have accepted, and have agreed to be bound by, the Terms of Use. Content: This Content is offered by the Province of Ontario’s Ministry of Northern Development and Mines (MNDM) as a public service, on an “as-is” basis. Recommendations and statements of opinion expressed in the Content are those of the author or authors and are not to be construed as statement of government policy. You are solely responsible for your use of the Content. You should not rely on the Content for legal advice nor as authoritative in your particular circumstances. Users should verify the accuracy and applicability of any Content before acting on it. MNDM does not guarantee, or make any warranty express or implied, that the Content is current, accurate, complete or reliable. MNDM is not responsible for any damage however caused, which results, directly or indirectly, from your use of the Content. MNDM assumes no legal liability or responsibility for the Content whatsoever. Links to Other Web Sites: This Content may contain links, to Web sites that are not operated by MNDM. Linked Web sites may not be available in French. MNDM neither endorses nor assumes any responsibility for the safety, accuracy or availability of linked Web sites or the information contained on them. The linked Web sites, their operation and content are the responsibility of the person or entity for which they were created or maintained (the “Owner”).
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Lamellar and Patchy Intergrowths in Feldspars: Experimental
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Mercian 11 F.Indd
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