File:Sodalite in nepheline syenite (Precambrian; Bancroft, Ontario, Canada).jpg
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Summary
| Description |
English: Nepheline syenite from the Precambrian of Ontario, Canada. (public display, Geology Department, Wittenberg University, Springfield, Ohio, USA)
Gray = nepheline Whitish = feldspar Blue = sodalite Nepheline syenite is a crystalline-textured, alkaline, intrusive igneous rock. Unlike an ordinary syenite, this rock has an appreciable nepheline content. Nepheline is a feldspathoid mineral - a "feldspar-like mineral". Feldspathoids have more aluminum and less silicon than the feldspars. They are less stable than feldspars and usually decompose in strong acids - they don't effervesce, but become gels. Nepheline is an aluminum-rich version of sodium feldspar - it has the chemical formula NaAlSiO4 (sodium aluminosilicate). The formula has also been cited as (Na,K)AlSiO4 (sodium potassium aluminosilicate). Nepheline has a nonmetallic luster, is usually whitish to grayish in color, is moderately hard (H = 5.5 to 6 on the Mohs Hardness Scale), forms hexagonal crystals, and has poor cleavage. It is an important rock-forming mineral in many syenites. It is usually mixed with albite feldspar (= sodium feldspar, NaAlSi3O8). The bluish-colored material is sodalite, which is another feldspathoid mineral. It has the formula Na8(AlSiO4)6Cl2 - sodium chloro-aluminosilicate. Locality: unrecorded/undisclosed site at or near Bancroft, southeastern Ontario, southeastern Canada |
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| Source | https://www.flickr.com/photos/47445767@N05/39816458570/ |
| Author | James St. John |
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This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/39816458570. It was reviewed on 19 June 2022 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
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| current | 08:19, 19 June 2022 | | 1,783 × 1,294 (1.72 MB) | Ser Amantio di Nicolao | Uploaded a work by James St. John from https://www.flickr.com/photos/47445767@N05/39816458570/ with UploadWizard |
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