Rock – an aggregate of minerals (mixture of minerals). Mineral – naturally occurring, inorganic,...
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Transcript of Rock – an aggregate of minerals (mixture of minerals). Mineral – naturally occurring, inorganic,...
Minerals
Rock – an aggregate of minerals (mixture of minerals).
Mineral – naturally occurring, inorganic, crystalline solids, with a definite chemical composition.
All minerals are rocks, but not all rocks are minerals!
Minerals vs. Rocks
Granite (rock)
mixture of:
Feldspar(mineral)
Biotite(mineral)
Quartz(mineral)
1. Crystal Form External expression of a
mineral’s internal orderly arrangement of atoms.
Size of the crystal is based on time & available space.
Properties of Minerals
Crystal Shapes:
Cubic Hexagonal
Tetragonal
Orthorhombic
Monoclinic
Triclinic
2. Luster Appearance /quality of light
reflected from the surface of a mineral.
Metallic vs. Nonmetallic.
Properties of Minerals
Choosing the Luster:Luster
Metallic
Shiny like a metal?
Nonmetallic
Vitreous(glassy)
Yes No
What kind of nonmetallic?
Earthy
Resinous
SilkyPearly
3. Color Outer appearance. Unreliable property. A mineral may have
several color varieties.
Properties of Minerals
4. Streak Color of the mineral in a
powdered form. Obtained by rubbing the
mineral across a streak plate.
Properties of Minerals
5. Hardness Resistance to abrasion or
scratching.
Properties of Minerals
1. Talc2. Gypsum3. Calcite4. Fluorite5. Apatite6. Feldspar7. Quartz8. Topaz9. Corundum10.Diamond
Softest
Hardest
Mohs’ Scale
How to test a mineral’s hardness
1. Start by moving an unknown sample across a sample with a hardness of 1.
2. If the unknown scratches the known sample, then it is harder….so keep testing the others until it doesn’t scratch it.
3. If it doesn’t scratch it, then it is softer than the known sample so it is lower on the scale.
4. If they scratch each other, they are the same hardness.
6. Cleavage Tendency for a mineral to
break along planes of weak bonding.
Smooth surfaces. Not to be confused with
crystals.
Properties of Minerals
7. Fracture Opposite of cleavage. Conchoidal fracture = curved
edges. Fibrous fracture =
splinters/fibers.
Properties of Minerals
8. Specific Gravity Comparison between the
weight of a mineral to the weight of an equal volume of water.
Comparison of densities. Written as the number of times
heavier/lighter than water.
Properties of Minerals
9. Other Properties Taste Elasticity Malleability Texture Magnetism Double Refraction Reaction to acids (HCl)
Properties of Minerals
8 elements make up 98% of the Earth’s crust (by weight).OSiAlFeCaNaKMg
Mineral Groups
Silicate GroupMinerals made of O and Si. ¾ of the minerals in the continental crust are
silicates. Silicon-oxygen tetrahedron (1 silicon to 4
oxygen) then bonded to another element(s). EXAMPLES:
Quartz, Feldspars, Micas
Mineral Groups
Carbonates GroupMinerals made of CO3 bonded with other
elements.EXAMPLES:
Calcite & Dolomite
Halides GroupMinerals made with members of the halogen
family.Formed through evaporation.EXAMPLES:
Halite & Fluorite
Mineral Groups
Sulfates GroupMinerals made of SO4 bonded with other
elements.EXAMPLES:
Gypsum
Oxides GroupMinerals made with Oxygen bonded with other
elements.EXAMPLES:
Hematite & Ice
Mineral Groups
Native Elements GroupMinerals that are pure elements (usually
metals).EXAMPLES:
Copper, Diamond, Graphite
Sulfides GroupMinerals made with Sulfur bonded with other
elements.EXAMPLES:
Pyrite
Mineral Groups
Ores – useful metallic minerals that are mined at a profit.EXAMPLES: Hematite (Iron), Sphalerite (Zinc),
Galena (Lead), Cinnabar (Mercury).
Industrial rocks & minerals – useful nonmetallic minerals that are mined at a profit.EXAMPLES: Fluorite, Sulfur, Halite (salt)
The amount of a mineral in a deposit must be concentrated several times it’s crustal percentage to be considered profitable.
Mineral Resources
Gemstones – Crystal forms of minerals that posses beauty of such quality that command a price when cut & polished.
Precious gems – have beauty, durability, size, and rarity.DiamondEmerald (Beryl)Ruby (Corundum)Sapphire (Corundum)
Mineral Resources
Semiprecious gems – only have one or two of the qualities of precious gems.EXAMPLES: Amethyst , Topaz, Garnet, Zircon
Non-mineral gems – stones that have value, but are not minerals.EXAMPLES: Coral, Amber, Pearl
Precious Metals – metallic minerals that have high value.EXAMPLES: Gold, Silver, Platinum
Mineral Resources