Igneous and metamorphic rocks

Sorry - no fossils here!

Igneous rocks form from molten rock, and rarely have fossils in them.

Metamorphic rocks have been put under great pressure, heated, squashed or stretched, and fossils do not usually survive these extreme conditions. Generally it is only sedimentary rocks that contain fossils.

Granular polished black and white rock surface

Augen gneiss, a metamorphic rock with white feldspars ‘eyes’, black biotite mica and colourless quartz.

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This is a metamorphic rock. The black and white rock is called amphibolite, and the large red crystals are pieces of garnet. Garnet is often cut and polished and used for jewellery.

This is an igneous rock called granite. Granite forms when a molten rock cools and crystallises.

It takes a long time for large amounts of molten rock to cool, so the crystals that form in granite are quite big. In this sample you can see invididual crystals of the minerals orthoclase (pink), quartz (grey), plagioclase (white) and mica (black).

This is a metamorphic rock called marble. Marble is formed when limestone (a sedimentary rock) is heated, and put under pressure. Marble is often polished and used as a decorative building stone.

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Igneous and metamorphic rocks

Do you know what these rocks are?

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