Mineral Criteria Inorganic: not made up of living things Inorganic: not made up of living things Naturally Occurring: exist in nature Naturally Occurring: exist in nature Crystalline Solid: regularly repeating crystalline structure Crystalline Solid: regularly repeating crystalline structure Consistent Chemical Composition: consistent, no variety Consistent Chemical Composition: consistent, no variety

Mineral Classes Silicates: contain silicon (Si) and oxygen (O) Silicates: contain silicon (Si) and oxygen (O) Nonsilicates: do not contain silicon (Si) and oxygen (O), 6 major groups Nonsilicates: do not contain silicon (Si) and oxygen (O), 6 major groups Carbonates, Halides, Native elements, Oxides, Sulfates, Sulfides Carbonates, Halides, Native elements, Oxides, Sulfates, Sulfides

Mineral Identification Color: easy to observe, minerals vary in color. Color: easy to observe, minerals vary in color. Many minerals are similar in color. Many minerals are similar in color. Small amounts of certain elements may greatly affect the color of a mineral. Small amounts of certain elements may greatly affect the color of a mineral. Weathered surfaces may hide the color of minerals. Weathered surfaces may hide the color of minerals. Examine freshly exposed surfaces. Examine freshly exposed surfaces.

Gold

Fluorite

We’re going streaking! Streak: color of the mineral in powdered form. Rub a mineral against a piece of unglazed ceramic tile (streak plate). The streak’s color may differ from the color of the mineral itself.

My precious, precious. Luster: light that is reflected from a mineral’s surface. Luster: light that is reflected from a mineral’s surface. Metallic: reflects light similar to polished metal. Metallic: reflects light similar to polished metal. Nonmetallic: All other minerals. Nonmetallic: All other minerals. Glassy, waxy, pearly, brilliant, and dull or earthy. Glassy, waxy, pearly, brilliant, and dull or earthy.

Galena

Hey, Mohs! Why I awtah… Mohs hardness scale: standard scale against which the hardness of minerals is rated. (1-10) Mohs hardness scale: standard scale against which the hardness of minerals is rated. (1-10) 1 is soft, 10 is hard 1 is soft, 10 is hard The bonds between the atoms that make up a mineral’s internal structure determines the hardness of that mineral. The bonds between the atoms that make up a mineral’s internal structure determines the hardness of that mineral. Test the hardness by scratching the minerals. Test the hardness by scratching the minerals. p. 111 Mohs Hardness Scale p. 111 Mohs Hardness Scale

Hardness Scale HardnessTest 1Does not scratch your fingernail 2 Scratches your fingernail, but not penny 3Barely scratches penny 4Easily scratches penny 5Barely scratches glass 6 Easily scratches glass, nail can scratch the mineral 7Nail cannot scratch mineral 8Scratches quartz 9Easily scratches quartz 10Diamond

Gypsum & Talc

Diamond

Cut! Cleavage: tendency of a mineral to split along specific planes of weakness to form smooth, flat surfaces. Cleavage: tendency of a mineral to split along specific planes of weakness to form smooth, flat surfaces. Break along flat surfaces that generally run parallel to planes of weakness in the crystal structure. Break along flat surfaces that generally run parallel to planes of weakness in the crystal structure.

Quartz

Acanthite

Time for a Break! Fracture: break unevenly into pieces that have curved or irregular surfaces. Uneven or irregular fracture: rough surface Splintery or fibrous fracture: looks like a piece of broken wood. Conchoidal fractures: curved surfaces.

Asbestos

Tiptopite (clear) Montgomeryite

Not again! Density: ratio of the mass to the volume of a substance. D=m/v Density: ratio of the mass to the volume of a substance. D=m/v Depends on the kinds of atoms that the mineral has and depends on how closely the atoms are packed. Depends on the kinds of atoms that the mineral has and depends on how closely the atoms are packed. Heavy metals have larger densities. Heavy metals have larger densities. Helps identifying heavier minerals easier. Helps identifying heavier minerals easier.

Special Properties Fluorescence: glow under ultraviolet light. Fluorescence: glow under ultraviolet light. Phosphorescence: continue to glow after ultraviolet light is removed. Phosphorescence: continue to glow after ultraviolet light is removed. Magnetism: attract metal, contain iron. Magnetism: attract metal, contain iron. Radioactivity: nuclei of some atoms are unstable. Radioactivity: nuclei of some atoms are unstable. Results in nuclei decay over time. Results in nuclei decay over time.

Magnetite

Lights, Camera, Action! Light rays bend as they pass through transparent minerals. Double Refraction: Light rays are split into 2 parts as they enter the crystal. Produces a double image.