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Rocks

• Composition

• Texture

Aggregate (combo) of 1+ minerals (can be made of the same mineral)

• Minerals, other materials

• Grain size, shape, layering

Minerals

• Defined chemical comp

• Defined physical properties

• Comma b/w minerals

Natural, inorganic, crystalline solid

• Balanced out formula

• Colors, cleavage, fracture, hardness, transparency, streak, acid reaction, magnetism, luster (at least 5)

• Possible substitiution

Cation

Positive charge ions (gives)

Anion

Negative charge ion (takes)

Noble gases

Nither gives or takes ions

Transitional metals

Varying positive charges

Polyatomic ion

1+ ions

Crystalline solid

Repeating atomic structures

• Orientation

• Angles

Naturally Occuring

• Created in nature

• Hard to mine

• Expensive

Synthetic

• Created in the lab

• Easy to create

• Affordable

Cleavage

Breakage along the planes of weakness/flat broken surface that shines

• Lined up bonds (“can pop off”)

• Examine planar breakage surfaces in 1+ specific directions

• Cleavage planes can be repeated

Fracture

Breakage, not along the cleavage plane

• Not a flat, smooth break

• Examine irregular or conchoidal breakage surfaces

Conchoidal Fracture

Curved & shiny surface

Uneven / Irregular Fracture

Irregular & dull surfaces

Basal Cleavage

• 1 cleavage direction

• Flat sheets

Prismatic Cleavage (@ 90º)

• 2 directions at 90º

• Elongated form, rectangular cross section (prism)

Prismatic Cleavage (not @ 90º)

• 2 directions not at 90º

• Elongated form, parallelogram cross section (prism)

Cubic Cleavage

• 3 directions at 90º

• Cube

Rhombic Cleavage

• 3 directions not at 90º

• Rhombohedon

Octahedral Cleavage

• 4 directions 

• Octahedron

Dodecahedral Cleavage

• 6 cleavage direction

Granite

Made of

• Quartz

• Potassium feldspar

• Plagioclase feldspar

• Biotide

• Amphibole

Beryl

When cut & polished, it’s an emerald

Calcite

Ca²⁺ + C⁴⁺ + 3O^2- = CaCO₃

Peridotite

Made of olivine

Olivine

2(Fe,Mg)²⁺ + Si⁴⁺ + 4O^2- = (Fe,Mg)₂SiO₄

Peridot

Gem-quality olivine

Quartz

Conchoidal fracture

Ortheclase (potassium feldspar)

• Prismatic cleavage @ 90º

• Uneven fracture

Lustre

Character of reflected light (metallic or non-metallic)

Crystal Form

Geometric shape formed by growth of crystal faces

Reaction to HCl (acid)

Chemical interaction of hydrochloric acid (HCl) & calcium carbonate (CaCO₃)

Streak

Colour of the mineral when crystal is powdered

Hardness scale

• 1

• 2

• 2.5

• 3

• 3.5

• 4

• 5

• 5.5

• 6

• 6.6

• 7

• 7.5

• 8

• 9

• 10

• Talc

• Gypsum

• Fingernail

• Calcite

• Copper wire

• Fluorite

• Apatite

• Knife blade/glass

• Feldspar

• Hardened steel file

• Quartz

• Porcelain streak plate

• Topaz

• Corundum

• Daimond