Ch. 3- Geology OUTLINE 17:56 Ch. 3- EARTH MINERALS: Minerals and Rocks INTRODUCTION: Rocks and minerals help determine the structure of the Earth system. Mineralogy - the branch of geology that studies the composition, structure, appearance, stability, occurrence, and associations of minerals. WHAT ARE MINERALS: Minerals are the building blocks of rocks: with the proper tools, most rocks can be separated into their constituent minerals. Limestone is made up of one mineral (calcite). Granite is made of several minerals. Minerals - a naturally occurring , solid crystalline substance, generally inorganic, with a specific chemical composition. Minerals are HOMOGENOUS: they cannot be divided mechanically into smaller components. NATURALLY OCCURING… To qualify as a mineral, a substance must be found in nature . Diamonds mined in South Africa ARE minerals/ Synthetic versions produced in labs are NOT minerals. SOLID CRYSTALLINE SUBSTANCE… Minerals are solid substances- they are neither liquid nor gases.
Crystalline - tiny particles of matter, or atoms, that compose it are arranged in an orderly, repeating, 3-dimensional array. Glassy or amorphous - (without form) solid materials that have no such orderly arrangement and are not conventionally called minerals. Examples: windowpane glass or natural glasses formed during volcanic eruptions. GENERALLY INORGANIC… Many minerals are secreted by organisms. Calcite - forms the shells of oysters and many other organisms, and it contains inorganic carbon. WITH A SPECIFIC CHEMICAL COMPOSITION… What makes each mineral unique is its chemical composition and the arrangement of its atoms in an internal structure. A minerals chemical composition either is fixed or varies within defined limits. Fixed ratios: Quartz (oxygen and silicon) and Olivine (iron, magnesium, and silicon). THE ATOMIC STRUCTURE OF MATTER : Atoms - ancient Greeks: atomos “invisible”; dictionary: anything considered the smallest possible unit of any material. John Dalton - an English chemist and the father of modern atomic theory , proposed that atoms are particles of matter so small that they cannot be seen with any microscope and so universal that they compose all substances. Atoms - smallest unit of an element that retains the physical and chemical properties of that element. Atoms - small units of matter that combine in chemical reactions and that atoms themselves are divisible into even smaller units.