Chapter 1 Minerals and Mineraloids When most people think of minerals, they usually imagine expensive gemstones like diamonds, emeralds and sapphires, or economic minerals like silver, gold and copper. While it is true that each of these substances is a mineral, they are all relatively unimportant as far as the make-up of the Earth is concerned. At last count, there were over 4000 minerals on and in the Earth, but only a handful are considered "valuable" in terms of financial reward (e.g., $$$). Minerals that make you money are considered economicand their value is determined on the basis of aesthetic reasons (e.g., sapphires, emeralds) or technological/industrial applications (e.g., diamonds, copper, sulfur etc.). In reality, the most important minerals are those that are most common because they make up the rocks that comprise the Earth's crust. We live on the Earth's crust. The common minerals are called rock-formingfor obvious reasons. One of the most important of the rock-forming minerals is quartz (SiO2). Almost every sand grain on the beaches at Dauphin Island, Gulf Shores and Fort Walton is a fragment of a quartz crystal, a major component in continental-forming rocks like granite. Quartz isn't particularly valuable in financial terms, but where would we be without it? Figure shows several schematics of crystals. From: Ford, W., 1932. Dana's Textbook of Mineralogy. John Wiley and Sons, New York, NY, 851p.
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