Minerals in Rocks
Minerals are defined by geologists as homogeneous, naturally occurring substances that possess a definable internal structure. They exhibit great diversity in forms, with some being incredibly hard, like diamonds, while others are softer, like talc. The variety found in minerals is partly due to the different physical and chemical conditions under which they form.
The section also discusses how rocks, consisting of combinations of minerals, can be composed of one or multiple minerals. For example, limestone is a rock made up of primarily one mineral, while most other rocks contain multiple minerals in varying ratios. Despite over 2000 identified minerals, only a few are plentiful in rock formations.
The study of minerals is important for both geologists and geographers: geologists concern themselves with mineral compositions, ages, and formations, while geographers study the relationships between minerals, landforms, and economic activities.
Minerals are often found in ores, which are accumulations mixed with other elements, and their method of occurrence varies:
1. Igneous and Metamorphic Rocks: These minerals may occur in veins or lodes and are created when minerals in liquid or gaseous form are forced toward the surface, cool, and solidify.
2. Sedimentary Rocks: Here, minerals occur in layered strata resulting from deposition and concentration processes, such as with coal and certain iron ores.
3. Residual Formation: This occurs when surface rocks decompose, leaving behind weathered materials containing ores, such as bauxite. Understanding these formations is essential for determining the cost and feasibility of mining minerals.