5616 x 3744 px | 47,5 x 31,7 cm | 18,7 x 12,5 inches | 300dpi
Aufnahmedatum:
5. Juni 2009
Weitere Informationen:
Thin Section Microscope Slide collected as Troctolite from Coverack, The Lizard in Cornwall. Known as 'Trout stone' on account of its attractive, multicoloured mottled appearance, it is a relatively rare rock. On cutting this particular sample was found to have a significant pyroxene content, which makes it a gabbro, though very much transtional between the two. Showing olivine which is partly altered to serpentine, and part still unaltered which shows bright colours in xpl. Also plagioclase, easily recognised by its twinning, but slightly distorted, and pyroxene- probably enstatite/bronzite. The red colouration is heamatite formed as a secondary mineral from iron in the olivine released by the serpentisation. This material is characteristic of the lithosphere - mantle junction known as the moho layer. Rarely seen, only when part of the oceanic crust is 'beached' on land as in the Cornish Ophilite at the Lizard.