Igneous rocks have a crystalline nature. This is why they glitter in the sun or look glassy in appearance. The crystalline nature of igneous rocks shows that they contain crystals,
Igneous rocks are usually very resistant to erosion and other climatic elements.
They are very hard and contain no animal or plant remains (fossils).
Igneous rocks do not occur in layers and as such are regarded as non-stratified rocks.
Some Igneous rocks have little holes on the surface e.g. pumice rock.
Igneous rocks may be dark, grey or brown in colour.