8th Grade Integrated Science Minerals and Rocks 8th Grade Integrated Science

Mineral Qualities What is a mineral? To be a mineral a substance must have ALL of the following qualities occur naturally - formed by nature, not by man form from an inorganic process- from things that were never living solid- tightly packed particles crystalline structure-the atoms line up in a repeating pattern, flat sides called faces meet at sharp edges and corners. definite chemical compostion- only certain elements in definite proportions.

Mineral Facts Almost all minerals are compounds SOME elements are found in their pure form, not part of compounds Copper (Cu), Gold (Au), Silver (Ag) Almost all solid, pure elements are metals

Mineral Identification Minerals can be identified from one another using specific properties. The internal atomic structure of the mineral determines its properties Color- the minerals color Not dependable to identifying most minerals b/c most minerals have many colors ex. Hematite is black, grey, silver, brown, red Very few common minerals have one color ex, sulfur (yellow) Many minerals are the same color ex. Magnetite, hematite, mica (black) Streak – the color of the minerals powder when rubbed on a streak plate VERY RELIABLE Streak for a mineral is ALWAYS the same color (no matter the color of the mineral

Mineral Identification Moh's Hardness Scale Hardness Mineral Description 1 Talc Fingernail scratches it easily. 2 Gypsum Fingernail scratches it. 3 Calcite Copper penny scratches it. 4 Fluorite Steel knife scratches it easily. 5 Apatite Steel knife scratches it. 6 Feldspar Steel knife does not scratch it easily, but scratches glass. 7 Quartz Hardest common mineral. It scratches steel and glass easily. 8 Topaz Harder than any common mineral. 9 Corundum It scratches Topaz. 10 Diamond It is the hardest of all minerals. Luster – the way the mineral shi-nes/reflects light Metallic- shines like a metal Non metallic – does not look like a metal Pearly - ex, mica Glassy – ex. Quartz, halite Dull/earthy – ex. Hematite (red) Waxy – ex. talc Brilliant – ex. Diamond Hardness – how easily a mineral is scratched fingernail (hardness = 2.5) copper penny (hardness = 3) Iron nail (hardness = 4) glass plate or steel knife (hardness = 5.5) steel file (hardness = 6.5) Ceramic tile (hardness = 7)

Mineral Identification Breakage Cleavage – mineral breaks along smooth, flat surfaces (due to internal structure of atoms) Fracture – mineral breaks unevenly, irregularly, or in jagged surfaces Density - (specific gravity how tightly packed the particles of a mineral are for a given volume compared to water Heavy – ex. galena, gold Medium – ex. quartz, feldspar Light – ex. mica, sulfur Other properties Chemical – will react with HCl (hydrochloric acid), bubbles or “fizzes” Magnetic Double refraction – bends light to create double image Fluorescence – glows in UV light Taste Smell

Mineral Lab Samples

Use of Minerals Ore - a naturally occurring solid material from which a metal or valuable mineral can be profitably extracted Metals – good conductors of heat and electricity Alloy – mixture of two or more metals and non metals (bronze, brass, steel) Gems – used in jewelry, hardness greater than 7, rare, valuable

How minerals form Organic processes Minerals form three ways Organic processes ALL minerals form by inorganic processes, BUT some form from organic processes as well Ex. ocean animals (clams and corals) produce shells and skeletons made out of calcite From materials dissolved in solutions Water evaporates leaving minerals behind Hot water heated by magma cools and minerals dissolved crystalize Vein- narrow channel of mineral that is different that the surrounding rock Cooling magma and lava Slow cooling = large crystals Fast cooling = small crystals