1. What is a mineral?
A mineral is a substance with these characteristics:
Solid
Naturally Occurring
Inorganic (never lived, although graphite, diamond, and calcite may be byproducts of organisms)
Definite Chemical Composition- for example, quartz (SiO2) or pyrite ( FeS2) or Halite (NaCl)
Crystalline Structure- has an ordered arrangement of atoms

2. Properties of Minerals: Tools for Identification
Hardness
Color
Luster
Streak
Cleavage
Fracture
Other: magnetism, conductivity, reaction to some acids
8/video/lbminera.mov

3. Hardness Geologist use the Mohs Hardness Scale
Developed by Friedrich Mohs about 200 years ago
Measures the resistance of a mineral to scratching
Scratch Test
A mineral of a given hardness will scratch a mineral of a lower number.

4. Color The most obvious property of a mineral is its color
Unfortunately, color is also the least likely to identify the mineral.
Quartz
Feldspar
Fluorite

5. Luster The way a mineral reflects light from its surface
Metallic – Shiny & Reflective
Vitreous- Glassy
Silky- Fibrous like silk
Pearly- Like mother of pearl or iridescent
Greasy- Appears greasy or oily
Waxy-Appears like it has a wax coating
Dull or Earthy

6. Streak
Streak is the color of a mineral’s powder when it is dragged across an unglazed porcelain plate called a streak plate
A mineral’s streak often differs from the color of its mineral.

7. Cleavage
Minerals that split along a flat plane of weakness have cleavage
Only one plane of cleavage
2 planes of cleavage
3 planes of cleavage

8. Fracture
Minerals that don’t break along a plane, but break with irregular shapes have fracture
Conchoidal breaks along concentric circles
Splintery fracture breaks like wood splinters.
Uneven fracture is a catch all name for all other types of fracture.
Conchoidal
Splintery
Uneven

9. Specimen A Specimen B Specimen C Specimen D Specimen E Specimen F
Cleavage or Fracture Present? Which Type?
Cleavage or Fracture Present? Which Type?
Cleavage or Fracture Present? Which Type?
Other distinguishing Features?
Other distinguishing Features?
Other distinguishing Features?
Specimen D
Specimen E
Specimen F
Cleavage or Fracture Present? Which Type?
Cleavage or Fracture Present? Which Type?
Cleavage or Fracture Present? Which Type?
Other distinguishing Features?
Other distinguishing Features?
Other distinguishing Features?

10. Name ____________________ Period ___ Date _______ Teacher _______________
Specimen
Color
(dark, light or mixed colors)
Streak
(Color of streak on streak plate)
Crystal Size
(fine or coarse
grained)
Luster
(glassy, pearly, silky, metallic, or dull/earthy)
Hardness
(see Mohs hardness scale)
Magnetic
(check with a magnet)
Reaction to Vinegar
(you may have to scratch the surface a little) A
_________ B C D E F

11. Specimen A
Specimen B
Specimen C
Specimen D
Specimen E
Specimen F

12. Mineral Identification Lab
Conclusion:
Use your collected data and mineral descriptions to identify each mineral.
Mineral Identification Lab
Response Questions: Please write answers in complete sentences!!
1. Use your chart to examine and evaluate your data. Do any of your minerals have the same color? How useful is color in determining a mineral’s identify.
2. Classify your minerals into two groups according to crystal size. How do you think each group of minerals formed?
3. Did any of your minerals have a glassy or sparkly luster? Why do you think that minerals with a glassy or sparkly luster are more important to people?
4. How would knowing the hardness of a mineral help you decide how the mineral could be used?
5. Was streak color ever different from the color of the mineral? How could streak be useful in indentifying minerals that are the same color?
6.What physical property was most useful in classifying minerals

13. Talc Mg3Si4O10(OH)2 Hydrous calcium silicate
Hardness- 1
Color – White to pale Green
Luster- Pearly
Distinguishing Features- Extremely soft: feels soapy. Impurities may increase apparent hardness. Commonly in scaly masses.

14. Halite (Rock Salt) NaCl Sodium chloride
Hardness – 2.5
Color – Colorless, salmon, pastels
Luster- Vitreous (Glassy) to greasy
Distinguishing Features- Dissolves easily in water. Breaks it 90o angles. Tastes salty.

15. Calcite CaCo3 Calcium carbonate
Hardness- 3
Color – Colorless white, rarely pastels
Luster- Vitreous (Glassy)
Distinguishing Features- Reacts to a strong acid by fizzing (If using a strong vinegar, you might need to rough up the surface by scratching it a few times with a nail or push pin before testing to get the reaction)

16. Pyrite FeS2 Iron disulfide
Hardness- 6
Color – Light brass-yellow
Luster- Metallic
Distinguishing Features- Black streak. Fragile. Note how streak is different than it’s color.

17. Magnetite Fe3O4 Iron oxide
Hardness- 6
Color – Black
Luster- Metallic
Distinguishing Features- Black streak. Magnetic. Grainy crystals common. Dense

18. Quartz SiO2 Silicate Hardness- 7
Color – Colorless, White, Gray, Brown, Pink, Purple, Yellow, Various
Luster- Vitreous (Glassy)
Distinguishing Features- Crystals are 6-sided prisms. Crystals may be in clusters, or line cavities in rock, Conchoidal facture. No Cleavage. Many types: Rock crystal, Amethyst, Citrine, Chert

19. Quartz is an important mineral with numerous uses
Quartz is an important mineral with numerous uses. Sand, which is composed of tiny Quartz pebbles, is the primary ingredient for the manufacture of glass. Transparent Rock Crystal has many electronic uses; it is used as oscillators in radios, watches, and pressure gauges. Quartz is also used as an abrasive for sandblasting, grinding glass, and cutting soft stones. Quartz is important in the production of soaps and ceramics. Transparent Rock Crystal is used in the study of optics. Quartz is essential in the computer industry, for the all-important silicon semiconductors are made from Quartz.
magnetite is an important ore of iron. Its perfect crystals are also famous among mineral collectors. This mineral is of scientific interest because of its special magnetic properties.
Halite is the source of common salt. Enormous Halite deposits are worked for salt. Salt has many uses, and must be heavily mined to satisfy demand. Some of its most famous uses are: as food seasoning for road safety to melt snow and ice as salt licks for cattle (these provide the cattle with salt, which is essential to their health) for medicinal purposes. Halite is also the most important ore of both sodium and chlorine.
Pyrite was once used as the main source of sulfur, but is now only a minor source for sulfur and iron. Pyrite was polished by the Native Americans in the early times and used as mirrors. Today, it is used as an ornamental stone, as well as a very popular stone for the amateur collector. It is sometimes used as gemstone by being faceted and polished for use as a side jewel in a ring, necklace, or bracelet.
Calcite is the primary ore of calcium. Calcite is indispensable in the construction industry, forming the base of cement. Many important chemicals are created from Calcite, as well as useful drugs. It is also crucial in the manufacture of fertilizers, metals, glass, rubber, and paint. The transparent Iceland Spar variety, in which the double refraction is very apparent, was used as Nicol prisms for polarizing microscopes and other optical devices.
Talc is an important industrial mineral. Its resistance to heat, electricity and acids make it an ideal surface for lab counter tops and electrical switchboards. It is also an important filler material for paints, rubber and insecticides. Even with all these uses, most people only know talc as the primary ingredient in talcum powder.