Knowing the different types of rock seems to be an important thing to learn when at school, but for most people it is knowledge that is unused later on in life. Different rocks though play an important role in everyday life, and igneous rocks in particular are important.
Igneous rocks are those rocks that form out of molten rock. Molten rock is commonly known as magma, although this specifically refers to molten rock below the earth’s surface. Molten rock that flows above ground is more specifically known as lava. Magma that solidifies becomes intrusive rock formations, whilst lava becomes extrusive rock. Thus there are two types of igneous rocks, intrusive and extrusive ones.
There are numerous igneous rocks, although relatively few are well known. The likes of granite, pumice, and basalt might be recognisable, but those rocks that include gabbro may be unknown.
Granite and gabbro are both intrusive igneous rocks.
Granite is probably the best known of the igneous rocks. Traditionally granite was a building material, and in antiquity was utilised in the building of the pyramids, and many of the other important buildings of the day. Today though granite is more likely to be found in the home, and is mainly used as countertops in kitchens. The colour and polish that can be applied to the stone make for an expensive, yet decorative work surface.
Granite is also sometimes utilised in the building of roads, headstones, and even curling stone or rock.
Gabbro is sometimes known as black granite, and has many of the same uses as granite. It does though have the additional properties of being high in metal content, including the likes of gold, silver and platinum.
Pumice and basalt are both extrusive igneous rocks.
Pumice is used in building work as breeze blocks or lightweight concrete, and pumice was one of the favoured building materials of the Ancient Romans. Today pumice is used in the cosmetic and cleaning industries. Pumice stones are used to remove dead and excess skin, but are also used as an abrasive in toothpastes. The abrasive nature of pumice is also made use of in cleaning materials.
Basalt is the most common of the extrusive igneous rocks. It is used when crushed as concrete aggregate for the building of roads.
There are though many more types of igneous rocks though, and the likes of peridotite and obsidian are particularly utilised in the manufacture of jewellery.
Igneous rocks may go unnoticed in daily life, and yet they have long been important building materials and cleaning materials.