Minerals All matter is made of elements A mineral: 1. occurs naturally 2. is a solid 3. has a definite chemical composition 4. has its atoms arranged in an orderly pattern 5. is inorganic Familiar minerals include quartz, halite, mica, gold, and diamond. Water is not a mineral, glass is not a mineral, a pearl is not a mineral. Minerals may be elements or compounds

Elements or Compounds 8 elements make up 98.5% of the crust’s total mass. By Volume: By Mass: Oxygen 93.8% 46.6% Silicon 0.9% 27.7% Aluminum 0.8% 8.1% Iron 0.5% 5.0% Calcium 1.0% 3.6% Sodium 1.2% 2.8% Potassium 1.5% 2.6% Magnesium 0.3% 2.1% The elements are almost always part of chemical compounds. Oxygen and Silicon are found in more than 90% of the minerals in the crust. Most minerals are compounds; quartz (Si and O), rock salt (NaCl) A few minerals are made of only one element; gold, copper, silver, sulfur, and diamond (C)

Bonds in Minerals Compounds are pure substances made of more than one kind of atom joined together. The atoms are held together with chemical bonds. Compounds come in two basic types: covalent and ionic. Covalent compounds share electrons to form molecules. Example: water In ionic compounds, atoms gain or lose electrons to form ions. Example: NaCl

Crystals Ionic solids exist as a solid in the form of an ionic lattice. The positive ions attract all of the negative ions, and vice versa. In the example of table salt (NaCl) the one-to-one ratio of ions results in a simple square-shaped ionic crystal:

How Minerals Form Many minerals form out of magma Atoms in magma move freely As magma cools, the atoms move closer together and combine to form mineral compounds The kinds of minerals depends on the elements present and in what amount The rate at which the magma cools determines the size of the mineral grains Some minerals form when water containing dissolved ions evaporates Minerals can be changed by heat, pressure, or the chemical action of water