Minerals (Review) Terms

Mineral is: Naturally Occurring--Not man made. Crystalline: solids whose atoms are arranged in a regular repeating pattern. Inorganic– Not derived form plants or animals. Specific chemical composition: All minerals have a specific chemical composition within a specific range.

Types of chemical bonds Ionic: one atom gives away one or more electrons to another atom. The giving atom becomes a positive charged cation. The receiving atom becomes negatively charged anion. Since + and – attract each other these atoms become bonded or bound to each other. Example NaCl.

Types of chemical bonds Covalent: One atom shares some of its electrons with one or more other atoms. Example: diamond is the covalent bonding of Carbon (C) atoms. H2O (though a non mineral) is a good example of covalent bonding. Oxygen has two empty slot in outer most energy level, and Hydrogen has one empty slot. To satisfy both they end up sharing electrons and a covalent bond results.

Types of chemical bonds Metallic: type of bonding found in metals. Electrons are loosely bond to any specific nucleus, and so can flow freely from one nucleus to the other. This is the reason that metals conduct electricity so well ( the electrons are so free to move.).

Atoms Parts of an atom: –Protons--+charged, relatively mass particles Number of protons in an atom determines what element it is, and is called the atomic number. –Neutrons– are neutral particles, having no charge. Similar to protons in size. Atoms with the same number of protons but different numbers of neutrons are isotopes of the same element.

Atoms Parts of an atom continued: –Electrons-- negatively charged, extremely light particles 1850 e- make up the mass of one proton (approximate). Behavior of the electrons determines the chemical behavior of a given element.

Other Atomic Terms Needed Ions: An atom without the same number of electrons and protons resulting in the atom not being electrically neutral. There are two types. –Cations—more protons than electrons, + charged. –Anions– more electrons than protons, - charged.

Other Atomic Terms Needed Electron Shells: electrons orbit the nucleus, but are restricted to discrete orbital distances from the nucleus called electron shells. –Each electron shell can hold a specific number of electrons ( ). –If a given atom has a full outer elecron shell, that atom is highly stable and reacts only weakly with other atoms (Noble gases). All other atoms will either give away, gain or share electrons.

Mineral Classes Based on the dominant chemical compound that makes up the mineral. –Silicates—Made of SiO4, in combinations with various elements such as calcium, magnesium, iron, etc. The silicates are the most abundant mineral type in the crust. Silicate ions form tetrahedral crystals. These tetrahedral shapes can form various forms such as isolated tetrahedra (olivine), rings (cordierite), single chains (pyroxenes), double chains (amphiboles), sheets (micas), and frameworks (quartz).

Mineral Classes Carbonates: Made from the carbonate ion CO3, in combination with various other elements. –Calcite is the common carbonate mineral, one form is aragonite (sea shells). There is also Calcite (CaCO3), and Dolomite ( CaMgCO3). Oxides: Made from oxygen combined with other elements such as iron, titanium, ect. Many economically important metals are mined as oxide ores.

Mineral Classes Sulfides: Made of sulfur with other minerals such as copper, iron, zinc, etc. Many economically important metals are mined as sulfide deposits. Sulfates: made from the sulfate ion (SO4) combined with minerals such as clacium, and barium. Gypsum is a sulfate mineral.

Mineral Classes Halides: salts of various kinds. NaCl is called halite, there are also KCl called Sylvite. Native metals: metals such as Gold, silver, copper etc.. Native elements: such as sulfur, diamond, graphite, arsenic.

Mineral Identification To identify minerals we use a variety of physical properties such as: –Hardness –Cleavage –Fracture –Luster –Color –Streak –Density –Habit You need to know which each of these refer to and how it is used.

Summary You should be able to do the following: –Define what a mineral is. –Discuss the Atomic theory of matter (atoms, protons, neutrons, electrons, etc.) –Know the types of chemical bonds in minerals (ionic, covalent, metallic) and how they work. –Discuss the basics of crystallization (how it takes place). –Know the different mineral classes. –Know how the minerals are identified.

SITES USED Thanks to Greg Anderson for use of lecture notes.