29 Section 2: Identifying Minerals Streak - the color of a mineral in powdered form.- the mineral is rubbedagainst a streak plate- streak is not affectedby air or water- more reliable thanmineral color
30 Cleavage and FractureCleavage - the tendency of some minerals to break along smooth, flat surfaces.
31 Cleavage and FractureFracture - the tendency of some minerals to break unevenly along curved or irregular surfaces.Conchoidal fracture
32 HardnessHardness - a mineral’sresistance to beingscratched.
33 DensityDensity - measure of how much matter is in a given amount of space. d = m / vgold = 19 g/cm3Specific gravity - the ratio of an object’s density to the density of water.gold = 19
34 Special Properties Fluorescence - glow under ultraviolet light. Calcite (red) and willemite (green)
35 Special PropertiesChemical reaction - look for bubbling when combined with an acid.CaCO3 + 2HCl = CO2 + H2O + CaCl2calcitehydrochloric acid
36 Special Properties Optical properties - such as double refraction. Same sample of calcite, but it’s rotated.
37 Special PropertiesMagnetism - attracts iron.Magnetite
38 Special Properties Taste Never taste a mineral without the teacher’s permission.Halite tastes salty.Borax tastes sweet.
39 Special PropertiesRadioactivityAutunite contains uranium.
40 Section 3: The Formation, Mining, and Use of Minerals
41 How Do Minerals Form? Limestones As water runs along the surface of the Earth andseeps through the ground, it dissolves minerals andcarries them to largebodies of water, wherethey crystallize on thebottom.
42 How Do Minerals Form? Evaporating Salt Water Minerals such as halite crystallize when salt waterevaporates.
43 How Do Minerals Form? Metamorphic Rocks Changes in pressure, temperature, or chemicalmakeup can form new minerals such as garnet.
44 How Do Minerals Form? Hot-Water Solutions Magma heats groundwater, which now more easilyreacts with and dissolves minerals. The mineralsthen crystallize out ofthe solution. Thisvein of gold wasformed this way.
45 How Do Minerals Form? Pegmatites Magma can move upward into these teardrop-shapedbodies. Pictured here is a sample of tourmaline froma pegmatite.
46 How Do Minerals Form? Plutons As magma moves up it may cool and solidify forming apluton.
47 Mining Ore: A mineral deposit large enough and pure enough to be mined for profit.
48 Mining Surface Mining Used to remove minerals located at or near the surface of the Earth.
49 Mining Subsurface Mining Used to remove minerals located too deep within theEarth to be surface mined.
50 Responsible Mining Potential mining problems: - Can disturb or destroy habitats- Waste products may pollute surface water andgroundwater
51 Responsible Mining Potential mining problems: Solutions: - Can disturb or destroy habitats- Waste products may pollute surface water andgroundwaterSolutions:- Reclamation: return mined land to its original state- Reduce need for minerals by recycling
52 The Use of Minerals Metallic Minerals - Have shiny surfaces - Do not let light passthrough them- Good conductors of heatand electricity
53 The Use of Minerals Nonmetallic Minerals - Have shiny or dull surfaces - May let lightpass throughthem- Good insulatorsof electricity
54 The Use of MineralsGemstones- Highly valued for beauty and rarity