Mineral Identification

1
Mineral Identification

• Color easy to observe, minerals vary in color.
• Many minerals are similar in color.
• Small amounts of certain elements may greatly
  affect the color of a mineral.
• Weathered surfaces may hide the color of
  minerals.
• Examine freshly exposed surfaces.

2
Salesite
3
Gold
4
Were going streaking!

• Streak color of the mineral in powdered form.
• Rub a mineral against a piece of unglazed ceramic
  tile (streak plate).
• The streaks color may differ from the color of
  the mineral itself.

5
My precious, precious.

• Luster light that is reflected from a minerals
  surface.
• Metallic reflects light similar to polished
  metal.
• Nonmetallic All other minerals.
• Glassy, waxy, pearly, brilliant, and dull or
  earthy.

6
Fluorite
7
Tiptopite (clear) Montgomeryite
8
Hey, Mohs! Why I awtah

• Mohs hardness scale standard scale against
  which the hardness of minerals is rated. (1-10)
• 1 is soft, 10 is hard
• The bonds between the atoms that make up a
  minerals internal structure determines the
  hardness of that mineral.
• Test the hardness by scratching the minerals.
• p. 111 Mohs Hardness Scale

9
Talc
10
Diamond
11
Quartz
12
Cut!

• Cleavage tendency of a mineral to split along
  specific planes of weakness to form smooth, flat
  surfaces.
• Break along flat surfaces that generally run
  parallel to planes of weakness in the crystal
  structure.

13
Acanthite
14
Time for a Break!

• Fracture break unevenly into pieces that have
  curved or irregular surfaces.
• Uneven or irregular fracture rough surface
• Splintery or fibrous fracture looks like a
  piece of broken wood.
• Conchoidal fractures curved surfaces.

15
Galena
16
Not again!

• Density ratio of the mass to the volume of a
  substance. Dm/v
• Depends on the kinds of atoms that the mineral
  has and depends on how closely the atoms are
  packed.
• Heavy metals have larger densities.
• Helps identifying heavier minerals easier.

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Special Properties

• Fluorescence glow under ultraviolet light.
• Phosphorescence continue to glow after
  ultraviolet light is removed.
• Magnetism attract metal, contain iron.
• Radioactivity nuclei of some atoms are
  unstable.
• Results in nuclei decay over time.

18
Lights, Camera, Action!

• Light rays bend as they pass through transparent
  minerals.
• Double Refraction Light rays are split into 2
  parts as they enter the crystal.
• Produces a double image.

19
Asbestos