Mineral ID

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Mineral ID

• How to identify a mineral by its properties

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Mineral Property 1 Color Streak

• Color is the first thing someone notices when
  they view a mineral.
• Color is also one of the big reasons that attract
  people to minerals.
• Generally speaking, color is not a good property
  to be used in the identification of minerals. It
  is usually the first property to confuse a novice
  collector into making an incorrect
  identification.
• Many minerals have different colors and some
  minerals' colors are identical to other minerals'
  colors.

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Mineral Property 1 Color Streak

• Streak is closely related to color, but is a
  different property because the color of the
  mineral may be different than the color of the
  streak.
• Streak is actually the color of the powder of a
  mineral. It is called streak because the proper
  way to test for streak is to rub a mineral across
  a tile of white unglazed porcelain and to examine
  the color of the "streak" left behind.

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Mineral Property 1 Color Streak

• Pyrite (known as "Fool's Gold") is always brassy
  yellow when found in crystals, even broken
  crystals, of any size but when powdered,
  produces a black streak.
• Gold's streak, by the way, is yellow!
• Hematite's streak is blood-red
• Galena's streak is lead gray

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Mineral Property 2Luster

• A minerals luster is the way in which light
  reflects from the surface.
• The two major types of luster are metallic
  nonmetallic.

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Mineral Property 2Luster

• Some other ways to describe luster are
• Dull - just a non-reflective surface of any kind
• Earthy - the look of dirt or dried mud
• Fibrous - the look of fibers
• Greasy - the look of grease
• Gumdrop - the look a sucked on hard candy
• Metallic - the look of metals
• Pearly - the look of a pearl
• Pitchy - the look of tar
• Resinous - the look of resins such as dried glue
  or chewing gum
• Silky - the look of silk, similar to fibrous but
  more compact
• Submetallic - a poor metallic luster, opaque but
  reflecting little light
• Vitreous - the most common luster, it simply
  means the look of glass
• Waxy - the look of wax

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Mineral Property 3How a mineral breaks

• When a mineral breaks it does so either by
  fracturing or by cleaving.
• Cleavage is the tendency of a mineral to break
  along flat surfaces.
• Crystal cleavage is a smooth break producing what
  appears to be a flat crystal face.
• Fracture is the tendency of a mineral to break
  into irregular pieces.

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Mineral Property 4Hardness

• A minerals hardness is its resistance to being
  scratched.
• A scale known as the Mohs scale is often use

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Mohs Scale
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Mineral Property 5Density

• Each mineral has a specific density.
• Density is the mass of a given space or in
  scientific terms the mass per unit of volume.
• For example, if you have two minerals of the same
  size one might be heavier than the other. The
  galena will be three times heavier than the same
  size of quartz.

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Mineral Property 5Density

• Geologists measure density by the following
• First they use a balance to determine the mass of
  a sample.
• Second, they place the mineral in water to see
  how much water it displaces.
• The volume of displace water the volume of the
  sample
• Third they use the following formula
• Density Mass/Volume

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Some minerals have specific properties

• Fluorescence some minerals glow when exposed to
  ultraviolet light
• Magnetic Some minerals are attracted to magnets
• Acid Some minerals react with acid by bubbling

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• Streak
• Powdered Color
• Luster
• How shiny
• Cleavage
• Breaks in sheets or blocks
• Density
• How much mass in a given volume
• Fracture
• Just crumbles breaks
• Hardness
• Can be scratched by