Crystal Formation and Growth Notes

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Crystal Formation and Growth Notes
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I. 4 Ways that Crystals Form

• 1) from a cooling melt - Magma (liquid) rock
  solidifies as it cools (Ex Lava flows)

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I. 4 Ways that Crystals Form

• 2) Precipitate from a
• solution or from
• evaporation - crystals
• form when a chemical
• / mineral gets too
• concentrated to stay
• dissolved in water

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I. 4 Ways that Crystals Form

• 2) Precipitate from a
• solution or from
• evaporation - crystals
• form when a chemical
• / mineral gets too
• concentrated to stay
• dissolved in water

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I. 4 Ways that Crystals Form

• 3) from a chemical reaction - a new
  substance (mineral) is formed by
  re-combining elements (minerals) that were
  already there

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I. 4 Ways that Crystals Form

• 4) from cooling gases
• (sublimation)
• usually form near
• volcanic vents
• hot springs

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II. Patterns of Growth
Crystals grow in one of five basic patterns
Blocky Radial Bladed Needle-like
Dendritic (Prismatic) (Acicular)
(Tree-like)
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II. Patterns of Growth
Blocky Crystals
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II. Patterns of Growth
Radial Crystals
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II. Patterns of Growth
Bladed Crystals
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II. Patterns of Growth
Dendritic (Branching) Crystals
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III. Crystal Growth

• A. Massive (adjective) - describes minerals made
  of masses of very tiny crystals or grains -
  usually form when the mineral cools very quickly.

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III. Crystal Growth

• Crystal Growth - the slower a crystal forms, the
  larger it will grow in size,
• (because it has more time to get organized into
  a larger lattice.)

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III. Crystal Growth

1. Crystalline (adjective) - describes mineral with
   large, distinct crystal shapes and faces
2. Crystal Face - smooth, flat, shiny surface of
   crystal found in many different geometric shapes
   squares, hexagons, etc. (easily visible in
   blocky crystal growth)

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IV. Mineral properties that depend on crystal
structure.

• Hardness -
• depends on crystal
• structure and the
• strength of the
• chemical bonds
• which hold the
• molecule together.

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IV. Mineral properties that depend on crystal
structure.

• (Ex Carbon atoms in diamond are held together
  by very strong covalent bonds,

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IV. Mineral properties that depend on crystal
structure.

• while the carbon atoms in graphite are held
  together by weak pi ( p ) bonds and split apart
  easily.)

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IV. Mineral properties that depend on crystal
structure.

• B. Cleavage - tendency for a mineral to split
  along a flat surface - occurs along a layer of
  weaker bonds called a cleavage plane

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IV. Mineral properties that depend on crystal
structure.

• C. Fracture - if a mineral does not have any
  layers of weaker bonds, the mineral will break in
  a more uneven, haphazard fashion (like broken
  glass or splinters).

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IV. Mineral properties that depend on crystal
structure.
C. Fracture - if a mineral does not have any
layers of weaker bonds, the mineral will break in
a more uneven, haphazard fashion (like broken
glass or splinters).