The Study of Minerals as part of Earth Science

The relationship of mineral science to several branches of the earth sciences is shown schematically in Fig. 1.1. Additional subdisciplines of earth science could have been added to the diagram, such as soil science, geochronology, and sedimentology, but the main reason for the schematic is to argue that a very large part of what is done in the earth sciences involves minerals in one way or another. Beginning with the subject of petrology (Fig. 1.1) and going clockwise from there, one may ask, "What is the mineralogical basis for each of these branches of earth science?"

FIG. 1.1. The central role of mineral science in the earth sciences

Petrology. The scientific study of rocks, their overall composition, their mineralogy, texture, structure and conditions of origin. Experimental petrology involves synthesizing rocks and minerals in the laboratory to evaluate the physical and chemical conditions under which they form.

Geochemistry. Much of geochemistry deals with the relative abundance, distribution, and migration of chemical elements (and their isotopes) in Earth and planetary materials that are represented by minerals, rocks, and soils.

Geophysics. This branch of earth science deals with such geologic phenomena as the temperature distribution of the Earth's interior and the source, configuration, and variations of the geomagnetic field. In all such investigations the physical properties of minerals and rocks are basic parameters to understanding the physical phenomena that are measured.

Structural Geology and Tectonics. A scientific discipline that evaluates rock deformation on both small and large scales. The scale of its investigation ranges from submicroscopic lattice defects in crystals to faulting and folding associated with mountain building and the large- scale upward and downward movements of the crust.

Meteoritics and Planetary Studies. The field of meteoritics is dedicated to the study of the chemistry and mineralogy of meteorite samples that have been collected on Earth. Planetary studies involve the study of rocks and soil (e.g., lunar regolith) returned from scientific missions to other planets. Such studies aid in an assessment of the geologic history of the planets from which the materials originated: asteroids, Mars, and the moon.

Environmental Geology and Mineralogy. Environmental geology is a scientific field that applies geologic research to the problems of land use and civil engineering. This includes reclaiming mined lands (with, e.g., sulfide minerals or radioactive minerals in waste dumps) and identifying geologically stable sites for housing of nuclear waste and the construction of nuclear power plants. Environmental mineralogy is concerned with the interaction of minerals (their surfaces, their fracture patterns, their particle size) with biological systems. An example of this is the role of natural and anthropogenic mineral dust and the occurrence of pulmonary diseases.

Economic Geology. This field of study is concerned with the distribution of mineral deposits, the economic considerations involved in their recovery, and the assessment of available reserves. Economic geology covers the extraction of ail materials from the Earth, including metal- rich ores, fossil fuels, and industrial materials such as salt, gypsum, building stone, and sand and gravel.