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Identifying Minerals. Unit 1:Sixth Grade. If you closed your eyes…. And tasted different foods, you could probably determine what the foods are by noting their properties Salty Sweet Crunchy Chewy You can also determine the identity of a mineral by identifying its properties!
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Identifying Minerals Unit 1:Sixth Grade
If you closed your eyes… • And tasted different foods, you could probably determine what the foods are by noting their properties • Salty • Sweet • Crunchy • Chewy • You can also determine the identity of a mineral by identifying its properties! • http://glencoe.mcgraw-hill.com/sites/dl/free/0078778085/164213/00044674.html
Mineral Identification • We use 7 different properties to help us identify minerals. • Color • Luster • Streak • Cleavage and Fracture • Hardness • Density • Special Properties
Color • Color is not usually the best way to identify a mineral • Some minerals, such as quartz, come in a variety of colors • Some minerals, like pyrite, when exposed to air, change color
Luster • The way a surface reflects light is called luster. • Shiny, dull • Minerals are described as metallic, submetallic or nonmetallic
Luster Metallic Nonmetallic • Bright, reflective, shiny • Example: Pyrite • Dull, reflective • Example: Talc
Luster • Non-metallic minerals are described using the words • Vitreous = glassy, brilliant • Waxy = greasy, oily • Silky = fibrous • Resinous = plastic • Pearly = creamy • Earthy = rough, dull
Streak • The color of a mineral in powdered form is called the mineral’s streak. • Its streak can be found by rubbing the mineral against a streak plate • The color left behind is the mineral’s streak. • The streak is not always the same color as the mineral sample. • Streak is more reliable than color!
Cleavage and Fracture • Different types of minerals break in different ways. • The way a mineral breaks is determined by the arrangement of its atoms
Cleavage and Fracture • Cleavage is the tendency to break along smooth, flat surfaces • Mica breaks into distinct sheets • Halite breaks into 90 degree angles in three directions
Cleavage and Fracture • Fracture is the tendency to break unevenly along curved or irregular surfaces • Quartz breaks in a curved pattern
Hardness • A mineral’s resistance to being scratched is called hardness. • To determine the hardness, scientists use the Moh’shardness scale.
Moh’s Hardness Scal • Scale of 1-10, softest to hardest • The more a mineral resists being scratched, the higher the rating is • Softest, with a hardness of 1: Talc • Hardest, with a hardness of 10: diamond. • To ID a mineral’s hardness, you scratch a mineral with reference material such as a fingernail, a penny or a nail.
Density • Density is a measure of how much matter is in a given amount of space • Matter: anything that has mass and occupies space. • Water, with a density of 1, is used as a reference point. • If a mineral is denser than 1, it will sink. • If a mineral is less dense than water, it will float
Special Properties • Some properties are particular to only a few kinds of minerals. • Fluorescence (glows under UV lights): Fluorite • Magnetism: Magnetite • Chemical Reactions: Calcite will bubble/fizz when a drop of weak acid is placed on it • Taste: Halite tastes salty • Optical: When calcite is placed over an image, the image will double. • Radioactivity