Mineral –a naturally occurring, inorganic, solid that has a crystal structure and a definite chemical composition Crystal – a solid with particles that form a repeating pattern Streak – color of the powder of a mineral Luster – how light reflects from a mineral Cleavage – splitting easily along flat surfaces Fracture – how mineral looks when broken apart in an irregular way Fluorescence – ability to glow under ultraviolet light Vein – narrow channel or slab of a mineral different from surrounding rock Ore – rock that contains a metal or economically useful mineral Smelting – melting of an ore in order extract the metal or mineral Alloy – a mixture of two or more metals Gemstone – hard, colorful mineral with a brilliant or glassy luster

Minerals more than 3,000 minerals identified must occur naturally in crust cannot come from something that was once alive is always a solid, with a definite volume and shape particles line up in a repeating pattern that is sometimes obvious and sometimes can only be seen under a microscope has a definite chemical composition, almost all are compounds each has its own specific physical and chemical properties used to identify it

Identifying Minerals hardness – use Mohs hardness scale which ranks 10 minerals from softest to hardest color – easily observed but can be used for only a few minerals, many minerals occur in a variety of color streak – observed by rubbing a mineral against a streak plate, streak will not vary among samples of same mineral luster – another way to determine mineral as ones containing metal will be shiny density – each mineral has a particular density crystal structure – crystals grow atom by atom to form a particular structure, classified into 6 groups based on number and angle of faces, called crystal systems cleavage – way mineral breaks apart, if splits easily along flat surface is said to have cleavage fracture – if breaks into irregular shape then is said to fracture special properties – some glow under ultraviolet light, some are magnetic, some radioactive, some react to acid, some have electrical properties

Mohs Hardness Scale

Formation of minerals minerals used today formed several billion years ago formed by crystallization of melted material or through crystallization of material dissolved in water size of crystal depends on rate of cooling, amount of gas in magma and chemical composition if magma stays underground and cools slowly will develop large crystals if magma close to surface and cools faster has no time for large crystals to form so will have small ones if solution of mineral rich liquid flows into cracks and crevices in earth will form a vein can have the solution evaporate which will leave thick deposits of mineral many valuable minerals found in or near volcanic activity or mountain building area

Lab: Determining Hardness, Color, Streak, and Luster of a Mineral Objective : The purpose of this lab is to determine the hardness, streak, color and luster of various mineral specimens. Materials: talcgalenacopper penny gypsumhematiteglass plate or microscope slide calcitepyritesteel nail fluoritebiotite orstreak plate feldspar muscovitemagnifying glass quartzhalite Safety Precautions: Use lab aprons. Follow normal laboratory precautions. Procedure: 1.Using your fingernail, the copper penny, glass plate and steel nail try to scratch each rock sample. Record your observations in Data Table 1. Data Table 1

Rock SamplesObservations Data Table 1

2.Complete Data Table 2 by scratching one mineral with another. If a mineral on Side A can be scratched by a mineral on Side B place a check in the correct space. If it cannot – leave it blank. A - Mineral Being Scratched Talc Gypsum Calcite FluoriteFeldspar Quartz Talc Gypsum Calcite Fluorite Feldspar Quartz B Mineral Used to Scratch Data Table 2

3. Now use Data Table 1 and Data Table 2 to determine where each sample will fall on Mohs Hardness scale. Place the samples on order from softest (1) to hardest (10) on Data Table 3. Data Table 3 MineralHardness Number

4. Use a streak plate to determine the streak for each sample given. Place your findings in Data Table 4. Mineral Color of Mineral Color of Streak Data Table 4

5.Observe the luster of each sample and place your observations in Data Table 5. MineralLuster Data Table 5

Conclusions: 1. Based on your findings which minerals were the four hardest? 2. Which samples would you recommend a person use for a counter or a floor in a kitchen that is being remodeled? 3. When given an unknown sample how would you go about determining what that sample is, using the tests from this lab?