Silicate Structures Silicate minerals that are structured so that none of the oxygen atoms are shared by tedrahedrons have an isolated silicate structure. If two oxygen atoms of each tetrahedron are shared with adjacent tetrahedrons, the result may be a chain of tedrahedrons, a chain silicate structure. When each tetrahedron shares three oxygen ions, the result is a sheet silicate structure. When all four oxygen ions are shared by adjacent tetrahedrons, a framework silicate structure is formed. Plummer and McGeary, 1988 Silicate Structures Plummer and McGeary, 1988 Minerals To be a mineral in the geologic sense of the term, a substance must satisfy five conditions: 1. 2. 3. 4. 5. It must be a crystalline solid It must occur naturally It must be inorganic It must have a definite chemical composition It must possess characteristic physical properties Plummer and McGeary, 1988 Plummer and McGeary, 1988

Physical Properties Color (Renk) Streak (izgi rengi) A pulverized mineral gives a color, called a streak, that is usually more reliable than the color of the specimen itself Luster (Parlaklk) The quality and intensity of light that is reflected from the surface of a mineral is termed luster. Crystal Form (Kristal ekli) The crystal form of a mineral is set of faces that have a definite geometric relationship to one another Plummer and McGeary, 1988 Fracture (Krk yzeyi) Fracture is the way a substance breaks where not controlled by cleavage Cleavage (Dilinim) Cleavage is the ability of a mineral to break along preferred planes Specific Gravity (zgl arlk) Ratio of the mass of a substance to the mass of an equal volume of water Hardness (Sertlik) Plummer and McGeary, 1988 Intergrown cubic crystals of fluorite Planer Cleavage in Mica Quartz

Conchoidal Fracture in Glass Magnetism (Manyetizma) Property of a substance such that it will spontaneous orient itself within a magnetic field. Magnetite (Fe3O4) has this property and it can be used to distinguish it from other nonmagnetite iron oxides, such as hematite (Fe2O3). Double Refraction (ift krlma ) Light is split or refracted into two components giving rise to two distinct images.