Rocks Vs. Minerals Many colors Many crystal shapes Many ingredients Made of many compounds Mostly one color Repeat same crystal shape All the same stuff- made of one compound

Non-mineral rocks? Coal- made of compacted plant material Limestone- organic calcium carbonate from shells Coquina- made of cemented shells Amber- hardened plant resin

Characteristics of Minerals

Mineral Characteristics Naturally occurring Inorganic Solid Crystalline (has a repeating arrangement of atoms) Specific chemical composition

Naturally Occurring Minerals are made by processes that occur in or on Earth. Mineral are NOT man made

Formed by Evaporation Salt does this

Formed by Cooling Magma You could compare this to poured sugar

Formed by Precipitation Geodes Stalactites and Stalagmites Rock candy

Inorganic Not organic Organic substances are made by living creatures and include proteins, carbohydrates, and oils We will talk about exceptions to this later.

Crystalline Structure Crystal - a solid in which the atoms are arranged in a regular repeating pattern.

Crystalline Structures

Chemical Composition 98.5% of Earth’s crust is made of: oxygen silicon aluminum iron calcium sodium potassium magnesium

Families of Minerals Silicates- biggest group, makes up 90% of all igneous rock minerals. Over 50% of Earths Crust is made of Silicon and Oxygen. Other mineral families Oxides, halides, carbonates, sulfides, sulfates, nature elements

Chemical Composition All minerals have a specific chemical composition silver=only silver atoms diamonds=only carbon atoms halite = salt = NaCl Quartz = SiO2

Most Rocks are made of Minerals!!!!!

Non-mineral rocks? Coal- made of compacted plant material Limestone- organic calcium carbonate from shells Coquina- made of cemented shells Amber- hardened plant resin

Physical Properties of Minerals

Physical Properties of Minerals Color Streak Luster Density Cleavage Fracture Hardness

Color The color a mineral. This can be misleading.

Streak The color of the mineral’s powder. It is sometimes different from the color of the sample, but most forms of the mineral have the same streak color.

Luster Shininess or lack of shininess

Density mass per volume usually reported in “specific gravity,” which is density compared with water

Cleavage Tendency to break along planes of weakness in a predictable way

Fracture Tendency of a mineral to break randomly, without cleavage. A mineral either has cleavage or fracture. Not both.

Hardness what minerals it can scratch and what minerals can scratch it.

How it works If the mineral gets scratched, it is softer than the substance you used. If the mineral scratches the substance, it is harder than the substance you used. What it tells you is how strong the bonds are between atoms in the mineral.

Mohs Hardness Scale

Other characteristics Smell- sulfide minerals like pyrite smell like rotten eggs Taste- halite is salty Magnetism- magnetite is attracted to a magnet Reacts with acid- limestone fizzes