45 terms

Earth Sci: 4 - Identifying Minerals

STUDY
PLAY
Mineral
naturally occruing inorganic solid with definite chemical composition and crystalline structure
Atoms in highest abundance in the Crust by mass
OSiAl FeCal NaKMg
Oxygen 47% & Silicon 28%
Aluminum Iron Calcium Sodium Potassium Magnesium
Three types of Bonds that hold atoms in Minerals
Covalent, Ionic Metallic
Calcite
"+" acid test
perfect cleavage in 3 directions @ 75°
Hematite
gray metal or brown color
red brown streak
Olivine
olive green color
glassy luster, hardness 6.5
Sulfur
yellow color
sulfurous odor
Halite
cubic crystal
salty taste
dissolves in water
Biotite
one directional cleavage
can be thin as paper
dark color
Quartz
hardness of 7
hexagonal crystal
Feldspar
most abundant mineral family on Earth
pink, white, gray or brown, hardness 6, 2 directional cleavage
Galena
metallic gray luster
cubic crystal
specific gravity ~10
Pyrite
Brass yellow, metallic luster, cubic crystals
fools gold
Amethyst
6-sided prism ending in 6-sided pyramid with glassy purple color
hardness 7
Magnetite
black or gray with brownish tint
metallic luster and magnetic
Gypsum
pearly luster
scratched by fingernail
Graphite
marks paper
Classification based on Chemical Composition
Slicate, Carbonate, Sulfate, Halide, Oxide and Sulfide, Element
Silicates (SiO₂) are the most abundant
Classification based on Use
Industrial, Ore, and Gem
Industrial Mineral
A naturally occurring rock or mineral that can be used "as-is" for manufacturing or chemical production
gypsum, halite, limestone, and talc are examples
Ore
-a rock or mineral from which a valuable constituent, especially a metal, can be profitably mined or extracted
Gemstone
A durable and lustrous mineral cut and polished for use as an ornament or jewelry
-used for jewelry, decoration, grinding and polishing
What are some examples of metals and how are they used?
ex: aluminum, iron, copper, silver
-can be stretched into wire
-flattened into sheets
-hammered without breaking
Five locations minerals can form?
Water near Earth's surface
Hydrothermal Deposits
Cooling Magma
Metamorphic Rock
The Mantle
How do minerals form from magma?
-Minerals form as hot magma cools
-Slow cooling underground = large crystals
-Fast cooling at surface = microscopic crystals
How do minerals form from hot water solutions?
-Water below the earth has been heated by magma
-The hot water causes the minerals to dissolve into solutions
-When the solution cools, the elements or compounds leave the solution and crystallize as minerals
What are some examples of minerals formed by evaporation?
gypsum (CaSO4), calcite (CaCO3), halite (NaCl)
What are veins?
narrow channels of pure mineral (often metal) that are different than the surrounding rock
What minerals are from the mantle?
Diamond and Olivine (peridot)
Common Tests for Mineral Identification
Color
Luster
Crystal Shape
Streak
Acid test
Fracture
Cleavage
Hardness
Specific gravity
Color
-Often is the first quality seen in a mineral
-Least useful property of a mineral
-Most easily observed
-Can use to ID a few minerals
Luster
-The way a mineral reflects light
-Either metallic or nonmetallic
ex: metallic = mineral shines like a metal (pyrite)
ex: Nonmetallic = doesn't shine like metal (diamond)
Crystal
-Crystals are geometric solids which contain smooth surfaces
-Exhibits good cleavage
-If allowed enough room minerals often show crystal shape
-ex: Cubic
-ex: Hexagonal
-ex: Triclinic
Magnetism
-Ability of strong magnet to be attracted to a mineral
Fluorescence
-Ability of a mineral to emit visible light when exposed to ultraviolet light (black light)
Streak
- Color of a powdered mineral
- Usually minerals are rubbed against unglazed white porcelain tile to get the powder
Fracture
- Describes the appearance of a broken surface
- can be uneven, irregular grainy fracture, or curving.
Cleavage
- The tendency of a mineral to break in smooth flat planes
- Cleavage is a very important property for identification
Acid Test
-Test that helps identify minerals containing calcium carbonate

-When acid is applied to certain minerals (carbonates) and fizzes, it gives off bubbles of carbon dioxide.
Hardness
-Ability to resist scratching
-Use Mohs Scale of Hardness to test (1=soft 10=hard)
-Can test with fingernail (2.5) copper (3) glass (5.5)
Crystal Shapes to Know
Symetric Crystals
cubic, tetragon, rhombohedron, hexagon, orthorhombic, monoclinic
Asymetric Crystals
triclinic
Ranking of Crystal Symmetry
Specifc Gravity
Physical property that compares the mass of a mineral to the mass of an equal volume of water
(tells us how many times heavier than water)
OTHER SETS BY THIS CREATOR

Flickr Creative Commons Images

Some images used in this set are licensed under the Creative Commons through Flickr.com.
Click to see the original works with their full license.