Rocks are rocks, minerals are minerals? What are the differences?

Tuchong Creative

First, let's look at the definition of what a mineral is. A mineral is a natural single substance or compound formed by geological processes. It has a fixed chemical composition and physical properties. For example, quartz feldspar is the basic unit that makes up a rock. This is a mineral.

What is rock? Rock is a collection of one or more minerals with certain chemical composition and physical properties. Rock is the main material that makes up the crust or upper mantle. The granite, basalt, limestone, sandstone, etc. that we are familiar with are all rocks.

The relationship between minerals and rocks is like a dish. Take fried tomato and eggs as an example. The dish of fried tomato and eggs is the rock, and the tomatoes, eggs and seasonings are the minerals. So the relationship between minerals and rocks is a subordinate relationship.

There are nearly 6,000 minerals found on Earth. How should we remember so many minerals? When naming, mineralogists will give different names according to the properties of the minerals. But there are still certain rules. For example, quartz can be called crystal when it becomes this kind of crystal. Some students may have heard of limestone and olivine. The names of these minerals all end with "stone". This is a very large category of minerals, which is called stone. Another interesting category is minerals ending with "ore", such as ferrocene, ferrocopper ore, galena, etc. Those ending with "ore" are all metal minerals.

There are also the granite, basalt, limestone, and sandstone that we just mentioned, all of which are followed by the word "yak". Therefore, we can use the names of these rocks and minerals to distinguish whether they are rocks or minerals.

Just now I mentioned that there are about 6,000 kinds of minerals. In fact, there are also hundreds of kinds of rocks. How can we distinguish so many rocks? Geologists classify all rocks according to their origins. They are mainly divided into three categories: igneous rocks, sedimentary rocks and metamorphic rocks.

The so-called igneous rock is a type of rock that is gradually formed during the process of magma rising and cooling. Sedimentary rock is a type of rock that is gradually deposited by weathering, erosion and transportation under external forces. This type of rock must be deposited in an area, such as rivers, lakes, and the sea, so it is also called sedimentary rock. This type of rock has a characteristic, that is, it has this layered structure. Sandstone, shale, conglomerate, etc. are sedimentary rocks.

The last category is called metamorphic rock. What is metamorphic rock?

Metamorphic rocks are formed by the combination of igneous rocks and sedimentary rocks in the earth's interior under certain temperature and pressure. This type of rock is called metamorphic rock.

Metamorphic rocks often retain some characteristics of the original rocks, such as granite gneiss. It is a type of rock formed by granite undergoing certain metamorphism. Therefore, it also retains certain properties of granite, including structure and texture. These three types of rocks can be transformed, and the process of transformation is called rock cycle.

This article is a work supported by the Science Popularization China Creation Cultivation Program

Author: Dong Hanwen, Ph.D. in Structural Geology

Reviewer: Gao Yuan, Associate Researcher, National Museum of Natural History

Produced by: China Association for Science and Technology Department of Science Popularization

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.