Properties of Minerals What is a mineral?

The Rules of the Mineral Every Mineral must follow these set of rules 1. Naturally Occurring 2. Inorganic 3. Solid 4. Crystal Structure 5. Definite Chemical Composition

Mineral Questions 1. Are pearls considered minerals? No, because they are made from animals. 2. Is naturally occurring glass considered to be a mineral? No, because it does not have a crystal structure.

Crystal Structure A crystal is a solid in which the atoms are arranged in a pattern that repeats again and again. Internal Arrangement of the Atoms A tetrahedral site lies in the center of a 4-

Definite Chemical Composition This means that a mineral always contains certain elements in definite proportions Quartz- always has one atom of Silica for every two atoms of oxygen

The Mineral Beryl EmeraldAquamarine

The Mineral Corundum Ruby Sapphire

Birthstones January - Garnet July - RubyGarnetRuby February - Amethyst August - PeridotAmethystPeridot March -AquamarineSeptemberSapphireAquamarineSapphire April – Diamond October - OpalDiamondOpal May – Emerald November - TopazTopaz June - Pearl December - ZirconPearlZircon

Identifying Minerals Each Mineral has its own specific properties that can be used to identify it. 6. Crystal Shape 7. Cleavage & Fracture 8. Special Properties 1. Hardness 2. Color 3. Streak 4. Luster 5. Density

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Mohs Hardness Scale 1 = Softest (talc or graphite) 10 = Hardest (diamond) How do you determine if one mineral is harder than the other? Perform a scratch test. If the mineral gets scratched it is softer than the object that scratched it.

Which mineral is gold? How would you be able to tell the difference?

Streak- the color of a mineral when it is made into a powder Pyrite(fool’s gold) is very similar in color to real gold, but Pyrite has a greenish-black streak and gold has a gold streak.

Luster- describes how light reflects off a minerals surface Metallic Luster- describes minerals that are shiny. Glassy Luster- describes minerals that look like they have a glassy surface, ex. Quartz *Minerals are usually described as having a metallic or non-metallic luster.

Which mineral has a metallic luster and which has a glassy luster?

Crystal Shape Every crystal has a characteristic shape that is due to its Crystal structure. Halite(NaCl or Salt)- will always have six sides and form a cube Hoppered pink Halite crystals from the evaporationHalite

Minerals will either break by cleavage or fracture? Cleavage- a minerals ability to split easily along flat surfaces Fracture- minerals which break with rough or uneven surfaces

Special Properties Fluorescence- some minerals glow under ultraviolet light ex.) Fluorite Magnetism- some metallic minerals are naturally magnetic ex.) Magnetite Effervescence- some minerals such as Calcite fizz when acid is placed on it Electrical Properties- a few minerals, such as quartz produce an electrical current

Fluorite

Scheelite(fluorescent mineral) ScheeliteScheelite with Mica.

Magnetite