October 28, 2021

I, Science

The science magazine of Imperial College

Peak District, UK, April 2009 – This is what your stylish kitchen worktop looks like in raw form.

Granite is among the hardest of the igneous rocks – those created when molten magma cools and solidifies.  It usually forms at subduction zones where one of the earth’s tectonic plates slips under another.

Rock melted by friction between the two plates rises through the continental crust and pools beneath the surface.  Sometimes this magma will spew out as volcanic lava, but if it can’t find a way through, it will sit there and slowly cool – producing granite with the big crystals seen by well-to-do cooks when making dinner (unless they’re so well-to-do that they have a maid of course).

If you have granite in your kitchen, next time you’re chopping onions, look closely at your worktop and you’ll probably see four types of crystals.  The transparent ones are quartz, the whiteish-grey ones are plagioclase and the big, pinky ones are orthoclase feldspar.  The little black specks are biotite.

Image from Boulder at Wikipedia.com