Suzanne Irwin, age 10, of Elkhorn, Neb., for her question:
WHAT IS GEOCHEMISTRY?
The combining form “ geo “ means earth. From this spring many of the words that are used to talk about the planet that is our home. Geology, for example, is the science of the earth, while geography is the study of the earth’s surface, climate, countries, peoples and products. Geodesy is the branch of applied mathematics that deals with the measurement of the earth.
Geochemistry is the science dealing with the chemical changes in, and the composition of, the earth’s crust and the earth in general. Geochemists explore the distribution and qualities of chemical elements and their isotopes throughout the earth, its crust, waters and atmosphere. They attempt to determine the natural processes that produced such a distribution.
One of the practical applications is exploration geochemistry, which is also called geochemical prospecting. In this field scientists locate deposits of petroleum, natural gas and ore.
Geochemical prospecting also involves analyzing and identifying very small amounts of diamonds, pitchblende and other minerals that can be found in surface soil, rocks, plants and ground water. The presence of tiny samples could well indicate that large deposits of the minerals can be found below the surface.
Still another branch of geochemistry is called isotope geology. By measuring the lead and strontium isotopes in various elements, scientists are able to estimate the age of the earth. Similar measurements of isotopes in lunar rocks and meteorites are now contributing knowledge about the beginnings of the solar system.
A great many geochemists can accept the Biblical explanation as to how our earth started, since “ on the first day” could well have taken several million years. Most of the scientists support the theory that the earth began as part of a huge cloud of dust and gases.
The gases and dust, they say, collected into a solid mass that grew larger by attracting nearby particles of matter. Various things happened within the mass to produce heat, which melted the materials that make up the earth. The heaviest materials sank to the earth’s center and lighter material floated upward. The materials then settled and formed layers, and the earth’s elements concentrated in the various layers.
One of the more interesting “ geo” words is geode. A geode is a hollow, stonelike formation that is often lined with crystals. Geodes average between two and six inches in diameter and can be found in many parts of the world. One of the most spectacular types is found in Uruguay and is called a water stone or hydrolite. This geode contains quartz crystals that were left when water that had silica in solution evaporated.