Minerals

What is a mineral? Naturally occurring inorganic (no living thing or remains) Solid Definite shape ( arranged in an orderly pattern) definite chemical composition

Is it inorganic? Coal? No, it is not a mineral- How is it made? Gold Yes, a mineral pearl No, not a mineral- How is it made?

Does it occur naturally? Quartz yes, a mineral- one of the last minerals to form from a magma chamber. steel no, not a mineral- How is it made?

Solid in crystalline form? mercury no, not a mineral- What is its natural form? glass not a mineral- What is its form? amorphous

Definite chemical composition? Graphite yes, C Concrete no, not a mineral- Why?

Rock forming minerals Over 3000 minerals only 20 are common, these are rock forming minerals two main groups- silicates and nonsilicates

Silicates 96% of the crust contain silicon (Si) and Oxygen (O) Feldspars are the most common silicate minerals, contain Ca, K, and Na Examples- Orthoclase and plagioclase Ferromagnesium- contain Fe and Mg example magnetite

Nonsilicates 4% of the crust No silica Six major groups carbonates-ex. Calcite halides- ex halite native elements- Made of one element ex. copper and silver oxides- hematite and corundum sulfates- gypsum sulfides- galena, pyrite

Identifying Minerals Characteristics of Minerals Each mineral has specific properties that provide useful clues for identifying minerals. Optical properties- properties will be identified by looking at the mineral. Tests- tools are used to run tests on the mineral.

Optical Properties Color Most easily observed ex. Sulfur is bright yellow, azurite is deep blue least reliable characteristic –quartz consists of many colors –weathering may hide true color –different minerals come in the same color

Luster Light reflected from the surface of a mineral metallic luster- like polished metal like silver All others are non metallic vitreous luster- reflects like glass pearly luster adamantine- brilliant luster ex. Diamond or gems other lusters include: waxy, greasy, dull, earthy

Crystal Shape Regularly shaped particles, or pattern. Most crystal shapes are hard to identify. six crystal systems –cubic ex. Halite, Pyrite –orthorhombic ex. Sulfur –tetragonal ex. Chalcopyrite –hexagonal ex. Plagioclase, Orthoclase –monoclinic ex. Micas –triclinic ex. Kyanite Bonds between minerals determine mineral properties

Cleavage The tendency to split along certain flat surfaces and is related to types of bonds ex. Mica (general name) splits easily in one direction, it has one perfect cleavage ( splits in parallel sheets) Example- biotite and muscovite

Fracture Some minerals do not break along cleavage planes instead they fracture or break unevenly into curved or irregular pieces splintery or fibrous fracture- looks like pieces of broken wood conchoidal- curved surfaces like the inside of a shell

Simple Tests Streak Test The color of a mineral in powdered form observed by rubbing the mineral against a piece of unglazed ceramic tile called a streak plate the streak is not always the same color as the mineral mineral that have a hardness higher than the streak plate can not be tested

Hardness Test The ability to resist scratching hardness does not mean resistance to cleavage or fracture the hardness of an unknown mineral may be determined by using Moh’s Hardness Scale

Moh’s Hardness Scale Mineral hardness common test talc 1 easily scratched by fingernail gypsum 2 can be scratched by fingernail calcite 3 can barely scratch a copper penny fluorite 4 can scratch a penny Apatite 5 can easily scratch a penny Feldspar 6 can scratch glass quartz 7 very easily/deeply scratches steel and glass topaz 8 scratches quartz corundum 9 no simple tests diamond 10 scratches everything

Make a sentence to help you remember talc 1TTWO gypsum 2 GGIRLS calcite 3 CCAN fluorite 4FFIGHT Apatite 5 AABOUT Feldspar 6FFEELING quartz 7 QQUITE topaz 8 TTROUBLED, corundum 9 CCAN diamond 10DDUDES?

Hardness Three tools are used to determine hardness- Finger nail- has a hardness of 2 Penny- has a hardness of 3 Glass plate- has a hardness of 5.5

Specific Gravity The ratio of the weight of the mineral to the weight of an equal volume of water. Each mineral has its own specific gravity Can be used to identify a mineral

Acid Test Used to easily identify calcite A drop of HCl dropped onto Calcite will cause it to effervesces. The bubbles are CO 2 gas. Dolomite also responds to the acid test but not as violently and only in powdered form.

Special Properties Magnetism- Can attach a magnet Fluorescence- the ability to glow under UV light ex. Calcite appears red under UV Phosphorescence- minerals that continue to glow after a UV light is removed.ex sphalerite

Special Properties con’t Double refraction- crystals that bend light in such a way that they produce a double image of any object viewed. Radioactivity- certain atoms have unstable electron or neutron arrangements. These minerals activate a Geiger counter.

End of Minerals

Work in your group to complete one of the following. Be ready to share. CreativeAnalyticalPractice Make a song or poem from your minerals notes. Make a drawing to represent your mineral notes. Make a flow chart to show information from your mineral notes. Make an analogy for the information in your mineral notes. Give a real life example for the information in your mineral notes. Explain in your own words to someone who missed class the main points of the mineral notes. Make a flow chart to show the information of your mineral notes.