|Type of Rock:||Magma:||Texture:||Mineralogy:|
|Igneous rock||Extrusive (magma reaches the surface to become lava).||Aphanitic (fine grained)||Composed mainly of pyroxene and Calcium-rich feldspar, with lesser amounts of olivine, and amphibole present. Mafic rock type (Mg and Fe rich).|
A thin section is made by grinding down a slice of rock which has been glued to a glass slide until it reaches a thickness of about 0.03mm (30 microns). At this thickness most minerals become more or less transparent and can therefore be studied by a microscope using transmitted light.
Back to rocks of Famous Monuments
© Guillermo Rocha, P. G. / Brooklyn College Geology Department