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 ID: 594987
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Slide1
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 (SiO
2
) or pyrite ( FeS
2
) or Halite (
NaCl
)
Crystalline
Structure- has an ordered arrangement of atomsSlide2
Properties of Minerals:
Tools for Identification
Hardness
Color
Luster
Streak
Cleavage
Fracture
Other: magnetism, conductivity, reaction to some acids
http://www.pearsonsuccessnet.com/snpapp/iText/products/0-13-036800-8/ch10/videoBlank.html?/ebook/products/0-13-036800-8/video/lbminera.movSlide3
Hardness
Geologist use the
Mohs
Hardness Scale
Developed by Friedrich
Mohs about 200 years agoMeasures the resistance of a mineral to scratchingScratch TestA mineral of a given hardness will scratch a mineral of a lower number.
http://zircon.mcli.dist.maricopa.edu/aaim/linear/L1.htmlSlide4
Color
The most obvious
property
of a mineral is its color
Unfortunately, color is also the
least likely to identify the mineral.
Fluorite
Quartz
FeldsparSlide5
Luster
The way a mineral
reflects light
from its surface
Metallic
– Shiny & ReflectiveVitreous- Glassy
Silky- Fibrous like silkPearly- Like mother of pearl or iridescent
Greasy- Appears greasy or oilyWaxy
-Appears like it has a wax coating
Dull
or EarthySlide6
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.Slide7
Cleavage
Minerals that split along a flat plane of weakness have
cleavage
Only one plane of cleavage
2 planes of cleavage
3 planes of cleavageSlide8
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
UnevenSlide9
Specimen A
Specimen F
Specimen E
Specimen D
Specimen B
Specimen C
Cleavage or Fracture Present? Which Type?
Cleavage or Fracture Present? Which Type?
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?
Other distinguishing Features?
Cleavage or Fracture Present? Which Type?
Other distinguishing Features?
Other distinguishing Features?Slide10
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
_________
Name ____________________ Period ___ Date _______ Teacher _______________Slide11
Specimen A
Specimen F
Specimen E
Specimen D
Specimen B
Specimen CSlide12
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
Mineral Identification Lab
Conclusion:
Use your collected data and mineral descriptions to identify each mineral.Slide13
Talc
Mg
3Si
4
O
10(OH)2 Hydrous calcium silicateHardness- 1 Color – White to pale GreenLuster- PearlyDistinguishing Features- Extremely soft: feels soapy. Impurities may increase apparent hardness. Commonly in scaly masses. Slide14
Halite (Rock Salt)
NaCl
Sodium chloride
Hardness – 2.5
Color – Colorless, salmon, pastels
Luster- Vitreous (Glassy) to greasyDistinguishing Features- Dissolves easily in water. Breaks it 90o angles. Tastes salty.Slide15
Calcite
CaCo
3
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)Slide16
Pyrite
FeS
2
Iron disulfide
Hardness- 6
Color – Light brass-yellowLuster- MetallicDistinguishing Features- Black streak. Fragile. Note how streak is different than it’s color.Slide17
Magnetite
Fe
3
O
4
Iron oxideHardness- 6 Color – BlackLuster- MetallicDistinguishing Features- Black streak. Magnetic. Grainy crystals common. DenseSlide18
Quartz
SiO
2
Silicate
Hardness- 7
Color – Colorless, White, Gray, Brown, Pink, Purple, Yellow, VariousLuster- 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, ChertSlide19
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 seasoningfor road safety to melt snow and iceas 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.