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Uploaded on:
12/03/2009 10:57:03
Type:
Digital Asset
File Size:
47.39 KB
Dimensions:
1000 x 667 pixels
187 views 4 downloads
P number: P524307
Caption: Photomicrograph of tachylite. Light: XPL, Magnification x 2. Camas na Cairdh, Muck, Invernessshire.
Description: The image is a photomicrograph of a glassy basaltic rock, taken under crossed-polarized lenses in order to show the interference colours of the minerals. British Geological Survey Petrology Collection sample number S 97037. Light: XPL, Magnification x 2. Light: XPL, Magnification x 2. The rock itself has a glassy matrix and is opaque. The spherical gas bubbles (vesicles) are mineralised, and this shows as a birefringent mineral with variable grey interference colours. Orange brown coloration around the vesicles represents alteration of the surrounding rock matrix. On Skye, Raasay, Rum, Eigg, Canna, Sanday and Muck olivine-basalt lavas identical with the plateau lavas of Mull are parts of an extensive and deeply eroded plateau that formed at the beginning of the Tertiary period. At this time, large amounts of mainly basaltic lavas were poured out over a land surface to form mountains of great height. In the Small Isles only a thickness of 1000-2000 feet of lavas remains after extensive erosion, most of the lavas are olivine basalts and mugearites.
Date taken: 01/01/2003
Photographer: Hyslop, E.K.
Copyright statement: NERC
X longitude/easting: 141400
Y latitude/northing: 780500
Coordinate reference system, ESPG code: 27700 (OSGB 1936 / British National Grid)
Orientation: Landscape
Size: 47.39 KB; 1000 x 667 pixels; 85 x 56 mm (print at 300 DPI); 265 x 176 mm (screen at 96 DPI);
Average Rating: Not yet rated
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