Aluminum Al Barium Ba Beryllium Be Boron B Calcium Ca Carbon C Cerium Ce Chlorine Cl Copper Cu Fluorine F Gold Au Hydrogen H Iron Fe Lead Pb Magnesium Mg Manganese Mn Mercury Hg Molybdenum Mo Oxygen O Potassium K Silicon Si Silver Ag Sodium Na Strontium Sr Sulfur S Thorium Th Tin Sn Uranium U Vanadium V Yttrium Y Zinc Zn Zirconium Zr We can compare the chemical elements to the letters of our alphabet. The letters, like the chemical elements, are fundamental building blocks, and they can be brought together in various combinations to form words. Minerals A _mineral_ can be compared to a word of our language. We combine letters to form a word, and nature combines certain chemical elements to form each particular mineral. For example, calcite, a mineral that is abundant in Texas, is always made up of the same proportions of the same three elements: calcium, carbon, and oxygen. [Illustration: A mineral is made up of chemical elements. The mineral _calcite_, for example, always consists of the same proportions of calcium, carbon, and oxygen.] Each mineral has its own characteristic internal structure and other properties. At ordinary temperatures, nearly all the minerals are solids rather than gases or liquids. (Water and mercury are the principal exceptions.) In addition, minerals are inorganic rather than being composed of plant or animal matter. When a single chemical element is found alone in nature as a _solid_, it is considered to be a mineral, too. Gold, silver, copper, lead, and sulfur are some of the chemical elements that can occur alone as solid minerals. When they occur this way, we refer to them as _native_ silver, _native_ copper, or _native_ sulfur. Although the element mercury is a liquid rather than a solid at ordinary temperatures, it too is a mineral when it occurs alone in nature. It is then called _native_ mercury. Rocks We have already compared the chemical elements to the alphabet and the minerals to words. We can now go a step further and compare rocks to sentences. We put words together to make sentences; nature puts minerals together to make rocks. A sentence does not have to be made up of a definite number of words, nor does a rock have to be made up of a definite number of minerals. Some rocks, such as granite, may be composed of several minerals. Others, such as dolomite and rock gypsum, consist of only one mineral.