Difference Between Primary and Secondary Minerals

The key difference between primary and secondary minerals is that primary minerals are formed from primary igneous rocks whereas secondary minerals are formed from weathering of primary rocks.

A mineral is a naturally occurring, inorganic solid substance that has a well-ordered chemical structure. It has a characteristic chemical composition and physical properties as well. According to this definition, naturally occurring means that a mineral is not a man-made compound. Inorganic means that it is not a product of an organism. In addition, it does not occur in either liquid or gas state at standard temperature and pressure conditions.

CONTENTS

1. Overview and Key Difference
2. What are Primary Minerals
3. What are Secondary Minerals
4. Side by Side Comparison – Primary vs Secondary Minerals in Tabular Form
5. Summary

What are Primary Minerals?

Primary minerals are substances that are formed from primary igneous rocks via original crystallization. That means; primary minerals form from solidification processes. The category of primary minerals includes essential minerals (that are used to assign a classification name to the rock) and accessory minerals (that are less abundant). Moreover, the dominant form of primary minerals is silicate mineral.

Usually, primary minerals form through a sequence or through sequential groups as stated by chemical and physical conditions. This formation occurs during magma solidification. Accessory minerals, a subtype of primary minerals, form from different steps of crystallization. However, the inclusion of a mineral within the category of primary minerals requires the formation of the mineral at early times.

An important difference between primary and secondary minerals is that the primary mineral substances are not altered because they form directly from the crystallization of magma. Therefore, primary minerals can be found in soil but they are not formed in soil. Primary minerals are useful in analyzing geochemical dispersion halos, and indicator minerals.

What are Secondary Minerals?

Secondary minerals are substances that are formed from the alteration of primary minerals. That means; secondary mineral forms when primary minerals undergo chemical and geological alterations such as weathering and hydrothermal alteration.

Secondary minerals are formed and found in the soil; e.g. gypsum and alunite are secondary minerals. A common form of a secondary mineral is clay.

What is the Difference Between Primary and Secondary Minerals?

A mineral is a naturally occurring, inorganic solid substance that has a well-ordered chemical structure. There are two main types of minerals as primary minerals and secondary minerals. The key difference between primary and secondary minerals is that primary minerals form from igneous primary rocks whereas secondary minerals from form weathering of primary rocks. Therefore, primary minerals occur in the soil but not formed in the soil, but secondary minerals occur in soil and form in the soil as well. Some examples of primary minerals include quartz, feldspar, muscovite, granite, etc. while some examples of secondary minerals include clay, gypsum and alunite.

Below infographic summarizes the differences between primary and secondary minerals.

Summary – Primary vs Secondary Minerals

A mineral is a naturally occurring, inorganic solid substance that has a well-ordered chemical structure. There are two main types of minerals as primary minerals and secondary minerals. The key difference between primary and secondary minerals is that primary minerals form from igneous primary rocks whereas secondary minerals from form weathering of primary rocks. Therefore, primary minerals occur in soil but not formed in soil but secondary minerals occur in soil and forms in the soil as well.

Reference:

1. “Primary Mineral.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 20 July 1998, Available here.
2. “Primary Mineral.” Wikipedia, Wikimedia Foundation, 19 Mar. 2020, Available here.

Image Courtesy:

1. “Elbaite” By Didier Descouens – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Clay pottery” By Knecht03 – Craig Knecht (CC BY-SA 3.0) via Commons Wikimedia