1. How to identify a mineral by its properties
Mineral ID
How to identify a mineral by its properties

2. Introduction
Which mineral properties are most important in identification.
Scientists have discovered up to 6000 minerals

3. Mineral Properties
To meet the definition of "mineral" used by most geologists a substance must meet five requirements:
naturally occurring
inorganic
solid
definite chemical composition
ordered internal crystalline structure

4. 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.

5. 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.

6. 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

7. Mineral Property # 2 Luster
A mineral’s luster is the way in which light reflects from the surface.
The two major types of luster are metallic & nonmetallic.

8. Mineral Property # 2 Luster
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

9. Mineral Property # 3 How 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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10. Mineral Property # 3 How 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.

11. Mineral Property #4 Hardness
A mineral’s hardness is its resistance to being scratched.
A scale known as the Moh’s scale is often use

12. Mohs Scale of Hardness

13. Mohs Scale Rating Type mineral 1 Talc Baby powder 2 Gypsum fingernail
What it can be
scratched by… 1
Talc
Baby powder 2
Gypsum
fingernail 3
Calcite
bronze coin 4
Fluorite
iron nail 5
Apatite
glass 6
Feldspar
penknife blade 7
Quartz
steel knife 8
Topaz
sandpaper 9
Corundum 10
Diamond

14. Mineral Property #5 Density
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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16. Mineral Property #5 Density
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