Granite: Rocks we know we know

November 9, 2017

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Identifying granite.  This is a new kind of rock identification guide for you.  A plain language, no silly business, get your rocks sorted in no time guide to “what rock is that?”

Igneous rocks: Granite

close detail of classic granite specimen from the area around Bowen, Queensland, Australia at rockhoundz.com.au

If it’s speckled pink and black and white it’s granite.  In general, the pink is feldspar, the white is quartz and the black is biotite or hornblende.

Granite is intrusive, felsic & phaneritic.  Have a look back at this post if you’ve forgotten what those terms are.

Granite comes from the same lava as rhyolite but with bigger crystals because it has cooled slowly underground.  The crystal size is one of the keys to identifying it as an intrusive igneous rock.

Right now you’ll find granite forming at the Yellowstone hotspot under the Yellowstone Caldera in the US.

This guide is designed to help you identify the classic rocks that are listed in most textbooks and found in most geology kits.  No curly examples, no red herrings – just the bog standard basics that you need to teach geology in the classroom.  Up next: Rhyolite

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