Cross polarised light micrograph of a thin section of a porphyritic basalt rock from Aberdeen,Scotland. The section is dominated by the large specimens of the minerals quartz & orthoclase feldspar. The quartz grains are clear grey,while those of orthoclase feldspar are darker grey. Large crystals,like these,embedded in a fine grained matrix are known as phenocrysts. A large twin crystal,known as a Carlsbad twin,is visible towards the upper right of the picture. A Carlsbad twin is a simpler variation of the multiple twins formed by plagioclase feldspar. Magnification x2.5 at 35mm size. Microcosmos P. 139 fig.7.23 | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / McNamee, Dr. Mike |
Taille de l’image : | 5037 px × 3310 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |