• 100 of 1000


Uploaded on:
12/03/2009 10:42:57
Digital Asset
File Size:
379.91 KB
1000 x 671 pixels
924 views 9 downloads
P number: P524291
Caption: Photomicrograph of basalt. Light: XPL, Magnification x 2. Edinburgh Castle Rock (excavation from tunnel), Midlothian.
Description: The image is a photomicrograph of a basalt from the volcanic plug on which Edinburgh Castle is built. The image is taken under cross-polarized light in order to show the birefringence colours of the individual mineral constituents. British Geological Survey Petrology Collection sample number ED 7367. Light: XPL, Magnification x 2. Light: XPL, Magnification x 2. The rock consists of an interlocking mass of small needles of plagioclase feldspar which have a random orientation. These mainly show grey birefringence colours. Crystals of olivine with very bright birefringence colours are scattered throughout the rock. Castle Rock is composed of a plug of Dalmeny type basalt rising almost vertically through Carboniferous Cementstone Group Strata. The plug may seal an orifice through which lavas of Lower Carboniferous age flowed. The Carboniferous basalts are classified according to the occurrence and type of phenocrysts. The Dalmeny type consists of olivine phenocrysts smaller than 2 mm. It may or may not have accessory clinopyroxene or plagioclase phenocrysts in lesser amounts.
Date taken: 01/01/2003
Photographer: Hyslop, E.K.
Copyright statement: NERC
Orientation: Landscape
Size: 379.91 KB; 1000 x 671 pixels; 85 x 57 mm (print at 300 DPI); 265 x 178 mm (screen at 96 DPI);
Average Rating: Not yet rated
Categories: Unsorted Images  


There is currently no feedback