Granite is one of the most common rock types in the continental crust. Granite has a coarse to fine-grained structure. Large parts of Sweden's bedrock consist of granite, especially in Småland and Norrland.
Together with tonalite and granodiorite, granite forms a large part of the continental crust. It is made up of quartz (grey), potassium feldspar (white or pink) and plagioclase (white), as well as varying amounts of muscovite (light), biotite (black) and hornblende (black); the colour is grey or red-speckled depending on the colour of the feldspar.
Granite is an igneous rock, deep rock to be more specific. Magmatic rocks are formed as solidification products of magmas (rock melts) in or on top of the earth's crust. When magma is pushed up, it cools because it is pressed against colder rocks. Slowly the magma solidifies. This is how granite and other deep magmatic rocks are formed.
Unlike a pure substance (element or chemical compound), a magma has no specific solidification temperature. Therefore, as the magma cools, solidification, or crystallisation, occurs over a wide range of temperatures. During solidification, the magma normally precipitates crystals of several different minerals.
There are several different types of igneous rock. Vulcanite (volcanic rock) is an igneous rock and is formed by the rapid cooling of magma at or near the Earth's surface. As a result, volcanic rocks become glassy or fine-grained crystalline. Examples of volcanic rocks are tuff, ignimbrite and pumice.
Bohus granite is the youngest granite in Sweden's bedrock, with an age of about 900 million years. The granite is a reddish or grey granite found in areas such as northern Bohuslän. It is fine- or medium-grained and contains numerous veins and veins of pegmatite.