GEOLOGY
MINERAL IDENTIFICATION LAB
Name___________________
Standards:
• Use appropriate technologies to collect, analyze and communicate scientific data.
• Describe the composition and structure of Earth’s materials.
Purpose: Learn how to identify minerals based on their properties.
Background: Although there are over 2500 naturally occurring minerals, only about 100 are common and
recognizable to an amateur observer. We can further reduce this list to a few dozen that make up over 95% of
the important rock-forming minerals. The samples you will analyze in the lab are representative of these few.
A recognition of these and their physical characteristics is important to a later understanding of rocks.
Procedure: For each numbered specimen, identify their properties from the following list and carefully note
these on the accompanying properties table. If possible study more than one specimen of each mineral as there
may be distinctive differences in the same mineral (such as color) that would help aid in a complete
identification. Be as thorough and precise as possible in your observations and analysis. Make use of the
mineral keys on your table to help in your identification. Identify a mineral’s properties on your own
observations and do not copy down things from the keys that you do not observe.
After you have studied and listed the properties of each mineral try to identify it and its class from the list given
in the lab (back of paper). All the specimens will be one of those in the list. Use a pencil to be able to make
changes later!!
Record the following items for each mineral in your data table.
 Number of sample – mineral samples are placed on numbers in your tray. Make sure you put minerals
back on their correct number.
 Color(s) – most obvious property, but not most reliable in identification. Color may vary in the same
mineral! Put down all visible colors in different specimens you have. Use a fresh surface.
 Luster – look of the mineral/how it reflects light. Luster will be either metallic or nonmetallic. If
nonmetallic, list type of luster (i.e., vitreous, pearly, earthy/dull, resinous, greasy).
 Streak – scratch the mineral across a streak plate and describe the powdered color. Remember, some
may not streak, but instead scratch the plate. This is an indication of its hardness. Most streak plates
have a hardness of 4-5. Also remember that streak color is usually not the same as a mineral’s visible
color.
 Hardness – resistance of surface to scratching. Perform various tests (glass, fingernail, penny, quartz)
to constrain the hardness of your mineral. If a mineral scratches something, it’s harder than what it
scratches. Refer to Moh’s scale of hardness to determine the mineral’s hardness. In most cases, you
will not have a single number, but instead a range (e.g., if something scratches glass but not quartz, it’s
hardness will be between 5 ½ and 7).
 Cleavage/fracture – determine whether the mineral has cleavage (breaks along a plane) or fracture
(does not break along a plane). If the mineral has cleavage, list the number of cleavage planes and if
they are good (easily seen) or poor (not easily seen). If the mineral does not have cleavage, it has
fracture. If it has fracture, list the type (i.e., conchoidal, irregular, splintery, fibrous).
 Other properties – anything else about your mineral that does not fit into the categories above.
Examples: magnetic, smell, striations (lines on surface), feel, acid reactivity (effervesces/bubbles with
acid, anything else (make good observations).
Mineral Classes and Names: minerals are listed under their class.
Silicates
Quartz
Feldspars – microcline
orthoclase
perthite
olivine
topaz
muscovite (clear mica)
biotite (black mica)
lepidolite (lavender mica)
hornblende
talc
tourmaline
pyroxine
Sulfates
gypsum
Sulfides
galena
pyrite
Carbonates
calcite
Elements
graphite
sulfur
copper
Oxides
hematite
magnetite
corundum
Halides (salts)
halite
fluorite
Questions
1. Which properties were most useful in identifying minerals?
2. Which minerals have high density (feel heavy for their size) and are metallic? Name at least two.
3. Which minerals were easiest to identify?
Hardest?
4. What mineral in the lab was the hardest (from Moh’s scale)?
The softest?
5. Name a mineral in the lab with 1 direction of cleavage.
Name one with 2 directions of cleavage.
Name one with 3 directions of cleavage.
Conclusion
Use the RACE method to answer the following question:
“How are the physical properties used to identify minerals?” (Hint: “how” does not mean to list the properties,
it means to DESCRIBE how they are used).