National treasure of global significance; dimension-stone deposits in larvikite, Oslo igneous province, Norway

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Authors:Heldal, Tom; Kjolle, Idunn; Meyer, Gurli B.; Dahlgren, Sven
Author Affiliations:Primary:
Geological Survey of Norway, Trondheim, Norway
Directorate of Mining, Norway
Volume Title:Geology for society
Volume Authors:Slagstad, Trond, editor
Source:Geology for society, edited by Trond Slagstad. Special Publication - Norges Geologiske Undersokelse, No.11, p.5-18. Publisher: Geological Survey of Norway, Trondheim, Norway. ISSN: 0801-5961
Publication Date:2008
Note:In English. 27 refs.; illus., incl. 1 table, geol. sketch maps
Summary: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. Finally, reserve estimates for the different types have been made, showing that some of the most attractive types have rather limited known reserves if the present level of production is maintained or increased. [R.A.H.]
Sections:Economic minerals and ore deposits; Various topics
Subsections:Non-metallic deposits
Subjects:Absolute age; Actinides; Construction materials; Dates; Dikes; Dimension stone; Evaluation; Fractures; Geochemical anomalies; Geophysical surveys; Granites; Igneous rocks; Intrusions; Joints; Lineaments; Magnetic anomalies; Metals; Mineral composition; Optical properties; Ornamental materials; Paleozoic; Pegmatite; Permian; Physical properties; Plutonic rocks; Production; Reserves; Style; Surveys; Tectonics; Thorium; U/Pb; Europe; Norway; Oslo Graben; Scandinavia; Western Europe; Larvikite; Oslo igneous province
Abstract Numbers:08M/2704
Record ID:2008128836
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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